Sacrifice

It was such a nice day. 4989 was humming a merry tune as he walked from the torso down towards the abdominal region of the body, finishing the tea he'd gotten earlier. He was supposed to meet up with 1146, as they were scheduled to go on patrol through the gut. It was one of the most dangerous places in the body, which was why even neutrophils tried to team-up when they were on duty there. The strange thing about the human body was that it was home to more bacteria than actual human cells, and most of those bacteria happened to be located in the intestine. Thankfully the majority was not only good but also vital for the body, helping it to absorb nutrients and water, as well as keeping their harmful cousins at bay.

Still, there were always those actively seeking to invade the body or those simply waiting for the right opportunity. In essence, there was no such thing as a quiet patrol through that particular region.

Eventually 4989 reached the agreed upon meeting point, finding himself on a little bridge across another street. The fluffy haired neutrophil looked around, until he spotted something that immediately made him smile. U-1146 had already arrived and not alone. By his side was AE 3803, a hand on her delivery cart, brightly smiling at her neutrophil boyfriend.

They stood together on the road below, keeping to the side as to not disturb the blood flow, probably saying goodbye as the two shared a kiss before parting. As she turned, AE spotted 4989 on the bridge and waved, the neutrophil happily returning the gesture, before she re-joined the crowd of erythrocytes, soon disappearing between the other red-clad cells.

1146 meanwhile walked up the steps to join him, a content smile on his lips. It was good to see him like this. Sure 1146 had always been satisfied with his role, even enjoyed parts of his job, he certainly cared for his friends and acted like a big brother around the platelets, but he had also always been one to worry quickly, to occasionally overthink. More than once 4989 had worried about his wellbeing, not just his health, but his mental state as well. Constant battles for the very survival of this world and perhaps more than just the occasional near-death experience; that could wear anyone out.

However things had changed since AE 3803 had come into his life, especially since they had discovered their true feelings for each other. At least those who knew him had noticed.

4989 was certain that he'd never seen his friend smile so much; he seemed more relaxed when things were calm, yet fiercer in battle at the same time, as if he was fighting with stronger conviction or renewed purpose. All things considered, regardless of what cells like Memory-T thought, he was doing better than ever. And 4989 couldn't be happier for them both.

"And what are you grinning about?" 1146 questioned when he joined him on the bridge.

4989 winked. "You two just look so adorable together. Would you like me to go alone?" He asked cheerfully, nodding toward the street AE had taken. "You could join her on her delivery."

His friend however merely shook his head. "Thanks, but we've agreed that we wouldn't compromise our duties, because of our relationship." His smile returned and the two began to walk down the road to head deeper into the digestive tract. "Besides, we'll meet again later."

"Alright; just wanted to offer it. I still owe you for taking my patrol, when I helped out AC 4293."

1146 lifted a hand, shaking his head. "Don't mention it. How is she doing, by the way?"

"Much better." He told him excitedly. "I've seen her a couple of times since and she seemed alright. She misses her older brother of course, but she's coping quite well from what I can tell." And she was smiling more again; he couldn't express how glad that made him.

His friend however furrowed his brow questioningly. "Sounds like you didn't talk much." He noted.

4989 smile faltered a little. "Not as often as I would like; her friends are not fond of leucocytes of any kind, so when they are around…." He explained disappointedly. Still, he had managed to talk with her a few times though, taking AE 3803 advice and bringing her tea and glucose whenever he spotted her on her own.

The first two times she'd been a bit confused by the gesture, but had never declined and thank him nonetheless. Their chats however were always brief, little more than catching up with each other before returning to their respective duties. It was partially his fault; 4989 simply wasn't sure how to talk with her. Even telling her about his day might gross her out; she just wasn't used to it like AE. Besides, he just couldn't help but notice that she appeared nervous, so it just seemed like a good idea to not aggravate that tension by sticking around.

What even were they? Strangers certainly not, so acquaintances? He wanted to be friends, but that term didn't seem quite right…yet. He had to do something about that.

"Wasn't it your original plan to remedy that that particular issue? Do something about that general fear towards us?" 1146 inquired, tilting his head a bit.

4989 sighed, rubbing his neck, feeling a bit put on the spot. "I know." He lamented. "But so far I've only managed to approach AC; you know, trying to help her cope with her scar and the death of her friend."

"I'm afraid that won't help much with the overall erythrocyte population."

"You're right, but I'm really not sure how to go about that." One red blood cell at a time was of course nonsense, but what was he supposed to do? Give out flyers? No, there had to be a more practical way. "Who knows; maybe by getting to know AC I can figure something out." If she could overcome her fear, she might have an idea how others could as well, though he shouldn't count on that.

For a moment his friend looked at him thoughtfully. "So, you really want to be friends with her."

"I like her." 4989 admitted, smiling again, his cheeks feeling warm. "She's nice and even quite fun, when she isn't intimidated; shame you weren't there at the wash station."

"The others told me a bit." 1146 mentioned, the corners of his mouth lifting a little. "And you wouldn't consider yourselves friends already?"

"Not really." He could hear the disappointment in his own voice and he looked at his chalk white clothes. "She's kinda nervous around me; I fear it's still difficult to see past the uniform."

The other leucocyte frowned again, but this time in a disbelieving manner. "You're sure? I've seen you talk to her the other day and you sounded just as nervous as her."

That was kinda true. "Just because I'm worried about saying the wrong thing." 4989 told him, even though he was a little embarrassed to admit it.

"And how do you know it's not the same with her?" 1146 pointed out with an encouraging smile and placed a hand on his friend's shoulder. "Perhaps she doesn't care about the uniform anymore, but just like you doesn't quite know what to say. All things considered, she's even newer to this than you."

4989 stared blankly at him. "Oh…" That he hadn't considered. He'd already made some experiences with AE 3803, but AC had probably never spent extensive time with a cell of another type.

"Besides, didn't you just console her after she lost her friend? You really think she would have let you hug her and keep her company all day if she didn't at least trust you? If she wasn't comfortable? And from what 2626 told me, she was very grateful for that." He shrugged, pulling his hand back again. "Maybe it's just me, but you seem to be friends in all but name."

"You think?" The fluffy haired neutrophil asked hopefully. All he had noticed was her apparent un-comfortableness and made a point not to outstay his welcome. Had he interpreted this all wrong? Maybe he should have thought about this a bit more.

"You might want to join her on a delivery." 1146 suggested, picking up on his friend's improved mood. "Your little five-minutes chats only get you so far." There was no denying that and it was something he'd like to change.

Yeah, now that he thought about it, maybe it was time to do just that. 4989 couldn't help but grin confidently. "Well, guess I have plans for later then." If she was alright with that. He just didn't have to stutter like during their initial encounters…. or cry; seriously he'd almost shed some tears when consoling her. Good thing that with his head on top of hers she hadn't seen it.

The other neutrophil chuckled at his enthusiasm, but 4989 didn't mind. "Tell us how it went. AE 3803 has been curious…" But he was suddenly interrupted by a slightly distorted voice.

"U-1146, U-4989; come in."

His friend reached for his transceiver. "U-1146 speaking."

"U-2048 here. You and U-4989 are on patrol in the intestine?" 4989 good mood dampened immediately. That didn't bode well; not that he had expected this patrol to be peaceful anyway.

"Just started our round." 1146 confirmed, his expression too looking much more serious than it had only moments ago.

"Good. We have an invasion at the colon and not the typical kind. We could really use any help we can get."

4989 took his own transceiver and joined in. "Do you know what germs we're dealing with?"

"Not yet, but I'd say some kind of E. coli. In any case, we have a bunch of destroyed epithelium cells. Even an M-Cells has been hit; they seem to have been poisoned." That really didn't bode well at all.

"We're on our way." 1146 merely replied gravely.

"Guess I'll be taking a shower before joining AC." The fluffy haired neutrophil noted half-jokingly, trying to lift the mood, if only for a second.

For a moment his friend's lips indeed curved to a faint smile. "I'm sure she'd appreciate it." Before he turned back to the transceiver. "2048; where do you need us?"


AC 4293 stretched her arms, feeling quite relaxed and rested. It had been an easy day so far and after enjoying a break at the colon, she had just started to head back to the small intestine, where she was supposed to pick up her next nutrient delivery. Maybe it would get her someplace interesting like the head, which had always been one of her favourite areas.

Perhaps she would cross paths with 4989 again too. She'd seen him almost daily since the splinter, often bringing her refreshments, asking how she was faring. Frankly she very much enjoyed his company. He was always so sweet and kind to her, not to mention that it was difficult not to smile when talking to him, thanks to his cheerful disposition. It was infectious; ironic really.

So it was a shame that she never quite knew what to say, something AC could kick herself for, in part because she wasn't quite sure what they were. They certainly weren't strangers anymore, beyond that she just wasn't sure.

It didn't help that he always left so quickly again. He made sure she was alright and left almost as quickly as he'd appeared.

A part of her had started to wonder, if he only sought her out because of pity. Of course she remembered his wish to not be feared by every none-immune cell, but that didn't mean he wanted anything further, that he wanted to be friends; perhaps that particular intention was just something she had wrongly interpreted from what he'd told her at the ear.

Maybe he was just being friendly, which strangely enough bothered her, made her nervous. What if he no longer sought her out once he noticed that she was fine and no longer struggling with the death of her friend? After all, she was one of millions of erythrocytes and so far he'd mostly seen her timid, vulnerable side. Way to make an impression.

Frustrated AC ran a hand over her face. Ugh, what was she thinking? He must have spent hours by her side, holding her, consoling her, when she had been at her lowest. He'd even opened up to her about his own, similar experiences. Certainly no one would do that just out of pity, right?

The auburn haired erythrocyte sighted. She really needed to stop with this self-loathing; it was a horrible new habit she'd picked up since…since FP's death.

Still, the issue remained that their recent conversations seemed to end before they really begun. If there was to be a chance for them to become friends that needed to change; surely she could do something about that.

If she met him during her delivery, perhaps she could invite him to join her, find out what he'd been up to. Strangely enough he never really spoke about his job, only his friends. Did he fear that she might get freaked out? Sure, killing and eating bacteria was undeniably a bit disgusting, but it had to make for more interesting stories than her deliveries. Besides, she was genuinely curious at this point. If these past few weeks had proven anything it was that she knew way too little about white blood cells.

AC thought back to the ear, the tussle at the wash station, the tea afterwards with him and his friends. It could work. Yeah, she could do this; she just needed to give it a shot.

The young erythrocyte reached the ascending colon, however almost as soon as she did all hell broke loose. A handful of erythrocytes came running from one of the smaller vessels to the main road she was on, screaming, shouting, causing a panic.

"Germs!"

"Run!"

Oh, come on.

When she'd been an erythroblast a neutrophil had taught her and her classmates how to escape. Just run. Don't stand around, trying to look what's after you, just run away; the whereto and how-far took care of itself. But it was never quite that simple.

As soon as AC started running, another red blood cell lost control of his cart and it crashed against her foot. The pain shot up her leg, making her see white for a moment and hissing sharply AC stumbled to her knees. The other erythrocyte continued to run, eyes full of terror, fixed on something behind her. Oh no.

"An erythrocyte?" A deep voice hissed pleased. "How convenient; I'm feeling a little peckish."

She should ignore the pain and run. AC knew that, but despite being frozen in horror something made her glance over her shoulder nonetheless. Behind her approached four centipede-looking creatures of a metallic green-black colour, though their heads were more snake-like, long fangs emerging from their upper jaws and coated with a watery film.

"Leave something for us." Another in the back spoke, its pink eyes fixed hungrily at AC, sending shivers down her spine.

As the one closest to her opened its jaws wide, preparing to bite, AC knew that she couldn't escape, not with her injured foot. Still, somehow she managed to stumble forward in a desperate attempt to do something, regardless how futile. Any moment now. It was lready casting its shadow upon her.

"Don't you dare touch her!"

The bacterium halted in its attack, and turned around. AC too stopped and did the same, recognizing that voice. Could it be?

A neutrophil dashed towards the germs like a white thunderbolt. He jumped and threw something, not knives, as AC saw it expand and reveal a white net that fell upon three of the bacteria. Immediately they screeched in pain, struggling against the fine threads that seemed to stick to them like fibrin.

The fourth, still standing just behind AC snarled threateningly, head lowered, a pair of its centipede-legs raised defensively. The neutrophil dodged a swing by one of those pointy appendages, leaped and landed on the bacterium's back.

AC gasped, the paralysing fear all but melting away in an instance. It really was 4989. In one hand he was holding what looked like a spear, though at second glance she realized that he'd tied one of his knives to a pipe, but something else really caught her attention. His expression was one of pure bloodlust and rage, almost making him look like a completely different person.

He was baring his teeth, his eyes wide and filled with murderous intent, fixed on his enemy. She'd seen him finish off a germ once, but she'd actually never really seen him fight. It was intimidating. He rammed the spear into the bacterium's back, the blade cutting through the membrane until it was deeply imbedded. The beast hissed, whirled around and tried to bite him, but the neutrophil nimbly dodged the frantic attack, drew a second knife with his left hand and stabbed into the germ's head from below. It stilled, the large body trembling, and with another slash, 4989 opened its throat, making sure it died.

Finally the bacterium collapsed and the neutrophil jumped off, letting his knife slip back into its sheath, before pulling out his spear.

And he turned to her.

It was as if someone had flipped a switch; his eyes softened, the murderous glare exchanged with a caring expression of genuine concern as he scanned her, gingerly stepping closer. It was such a contrast to the sharp precise movements he'd displayed in battle.

He crouched down next to her, making sure his spear pointed away. "Are you alright? Did they hurt you?" The fluffy haired neutrophil reached out with his free hand, but didn't actually touch her, perhaps because he was covered in bacterial cytoplasm, some dropping from his fingers.

AC tried her best to ignore his bloodied appearance and shook her head. "No. They didn't even get the chance." She assured him, feeling guilty for having actually felt intimidated by him a few moments ago. No matter how he looked, it really was still him.

4989 breathed out relieved, his shoulders sagging down. "Thank goodness."

"What were those?" She glanced over to the corpses, the net having etched into their membranes, which was admittedly somewhat disturbing.

"Pathogenic E. coli, a particular nasty version that produces toxins." He looked at her troubled. "Among them haemolysin."

AC's eyes widened in horror. "They would have…?" Getting killed swiftly was one thing, getting melted alive however…her cytoplasm shivered at the thought, her haemoglobin twisting in her chest.

EHEC

The strains of Escherichia coli known as enterohemorrhagic E. coli are toxin producing bacteria that are always human-pathogenic. They destroy cells of the intestinal epithelium via verotoxin, leading to watery diarrhoea. This toxin can also destroy cells of the blood vessel endothelium, causing symptoms such as bloody diarrhoea and spasmodic abdominal pain. Furthermore it can also kill immune cells ingesting the bacteria, such as macrophages, while another toxin, haemolysin, destroys erythrocytes.

Antibiotics are not recommended as they can further stimulate the production and release of toxins. Instead symptoms are treated, such as keeping the patient hydrated to counter the diarrhoea.

The fluffy haired neutrophil seemed to notice her reaction and looked her over once again. "You sure you have nothing on you? Your clothes?"

Thankfully that was impossible. "No; one wanted to bite me, but then you showed up." She smiled, genuinely grateful. "Thank you."

4989 returned her smile, his cheeks gaining a faint pink hue. "Glad I was in time." He told her, visibly relaxing.

"By the way, what did you use?" AC asked and nodded at the net he'd tossed across three of the germs. "Did you steal some fibrin from the platelets?"

This seemed to puzzle him for a moment. "What? No, this is mine; a weapon exclusive to us neutrophils. It's called a 'neutrophil extracellular trap', or NET for short."

NET

Neutrophil extracellular traps (NETs) are meshes composed of chromatin and antimicrobial proteins, which bind pathogens such as bacteria or fungal cells, trapping and ideally killing them. They can also stimulated other immune cells and an inflammatory response. There are several activation pathways, like through contact with bacterial lipopolysaccharides (LPS) of gram-negative bacteria such as E. coli or interactions with platelets that have been activated by damage endothelium cells.

"We can use it to capture and kill several enemies at once, make sure they don't escape. We have to be cautious though, or we risk trapping the wrong cells, block roads or cause an unwanted overreaction by the rest of the immune system. You see, they are made from nuclei acids, and usually their release is something that really gets all alarm bells going, because it indicates damaged or destroyed body cells. Even though we're just doing our jobs that can cause more harm than good in the end, kinda like an allergic reaction. So we gotta be careful when to use our NETs."

That sounded really dangerous, no wonder she hadn't seen it before; neutrophils even used their throwing knives sparingly. Still. "I'm glad you used yours this time." She confessed; who knew how the fight would have turned out otherwise.

"I was worried I wouldn't be able to take them all out in time." 4989 explained and once again he looked concerned. "You better stay clear of this place; frankly these shouldn't have gotten into the bloodstream in the first place, but I can't promise others won't make it as well."

"How did these do it?"

He pointed to somewhere behind him. "Collateral damage; the nearby blood vessel took too much and was torn open. Right now we're trying to contain the invading E. coli as best we can. I gotta go back help the others quell this invasion."

Now she worried. How many of these things were there? How long would he have to fight? Would they get reinforcements? "Stay safe, alright?" Was all AC however managed to say as he stood, clenching her fist.

He smiled one more time, his big eyes lighting up for a moment, before running off. "You too."


His mitochondria were pounding in 4989's chest as he ran. She was alright, she was safe now, but that had been far too close. He dreaded to think what would have happened if he'd arrived but a few seconds later. If that platelet hadn't shown him which way the bacteria had gone…the neutrophil shook his head and gripped his spear tighter. He couldn't think about what might have happened, what mattered now was preventing the germs and their toxins from spreading.

It didn't take him long to reach the battlefield again and not much had changed since he'd left. Neutrophils and macrophages alike were holding the line against the invaders, plenty of which were now lying scattered across the field of debris that had once been home to so many cells. As chaotic as everything appeared, it seemed as if the immune cells were at least managing to contain the bacteria for now.

He readjusted the grip on his weapon and leaped straight back into fight. "Die germ!" The E. coli screamed as he rammed the spear straight through its head, blade re-emerging through its mouth.

U-2048 greeted him with a grim smile, though keeping his eyes on the next wave of enemies approaching them. "Welcome back."

"Missed me?" The fluffy haired neutrophil asked brightly, wiping cytoplasm from his chin with the back of his hand. His friends were still where he'd left them and thankfully none seemed seriously injured, nothing appeared to go beyond scratches, bruises and torn uniforms.

"We started to worry." 2626 replied, pulling his blade from the body of another dead E. coli, strands of his bangs sticking together thanks to cytoplasm.

"You got the escapees?" 1146 asked and launched a batch of throwing knifes as a nearby germ that was about to attack 2048, making it flinch and stumble, allowing their friend to cut it down.

"All four, but seems like there are plenty left here." This was particularly troubling, given that this bacterial strain could do serious harm even in small numbers.

HUS

Haemolytic-uremic syndrome; a usually post-infectious, possibly lethal disorder, most commonly associated with bacterial toxins, such as the EHEC verotoxin. These cause damage to the endothelium cells, including those in the kidney's glomeruli, leading to apoptosis and an activation of coagulation factors as well as thrombocytes (platelets), creating clots in the small blood vessels. This results in haemolysis and eventually haemolytic anaemia, thrombocytopenia (low number of platelets in blood), kidney failure as well as a multitude of other symptoms.

"Yeah and more are getting in through the damaged epithelium." 2048 confirmed. "If we don't get this under control soon they and their toxins will spread."

"Any word on the lymphocytes?"

"Not yet." 2626 replied somewhat disappointedly and gave him what was probably supposed to be a meaningful look. "You know how it is."

The fluffy haired neutrophil couldn't help but groan. "This antigen representation takes way too long." Not for the first time.

Before one of the others could respond their transceivers demanded their attention. "Neutrophils!" 4989 new this voice; it belonged to one of their oldest comrades still patrolling the body. While neutrophils didn't use ranks like lymphocytes, seniority and experience were still respected. "Set up a perimeter! Push the invaders to the centre of the battlefield at all cost! Senior members of the division are to gather there now!"

The four childhood friends exchanged glances. "Do you think they want to…?" 2048 asked them, though they all knew the answer.

"These germs could kill the body, even if they don't make it any further than this." 1146 reminded them gravely. "I think they are going to do it."

4989 gulped, feeling his insides twist. "Can't we really just wait for the lymphocytes?" Maybe if they arrived in time, the tide could still be turned, negating the need for more drastic measures.

"With even macrophages getting poisoned and more of their toxin leaking into the blood system?" 2626 questioned, though the fluffy haired neutrophil saw him clutch his weapon tightly, the tension of his body revealing his displeasure at what was about to be done.

"They are not going to risk that." 2048 confirmed sombrely.

1146 took a deep breath and marched forth. "We have our orders. Let's make sure they're not doing this in vain."

The other three acknowledged as one. "Roger."


This was stupid. AC knew she shouldn't be here, but nonetheless she had not headed to the small intestine, but instead followed 4989. With her foot still hurting she was significantly slower than usual, but had eventually reached the outskirts of the battlefield. It was admittedly hard to miss.

Two of the buildings making up the blood vessel's inner wall, the endothelium, had been quite damaged, and the small gap between them usually only migrating cells like neutrophils could fit through, was now a wide hole. If there was another one in the intestinal wall, through which she assumed the invaders must have gotten in, erythrocytes could get swept out into the colon!

Carefully AC stepped closer; despite every instinct warning her, she just had to know or she would not find peace today, or be able to focus on her work properly. Standing at the hole, one hand against a wall, she suddenly felt a little draft, but nothing dangerous. Maybe it wasn't as bad as she'd feared.

The auburn haired erythrocyte took her first actual look at the battlefield and knew she was wrong. Where there had once been the homes and work places of muscle and conjunctive tissue cells, was now a field of debris littered with the corpses of bacteria. On the ground their bright red cytoplasm mixed with a watery liquid, likely the toxins, which actually seemed to erode whatever they touched. No wonder the intestinal epithelium and the blood vessels had taken damage.

Perhaps scarier however was the sight of a nearby macrophage, clearly wounded, pale as a neutrophil. Another of her kin had helped her to the edge of the battlefield, not far from where AC stood. Had she too been poisoned? Was that possible?

Watching the female immune cell sit down, leaning on her oversized cleaver, the young erythrocyte grasped her plait, squeezing it nervously. If even those cells could be harmed, what about neutrophils?

Turning her attention back to the fighting, she watched as the leucocytes began to encircle the invaders, herding them to an area near their point of entry. But that was the thing, they were driving them a certain direction, not killing them. How did they plan to dispose of so many enemies? The place was crawling with the green-black bacteria, fighting back with long fangs and sharp-edged, pointy legs.

As she watched AC 4293 couldn't help but notice that there were hardly any lymphocytes. She spotted a few B-Cells, probably providing assistance with unspecific antibodies, but it seemed as if the majority of the adaptive immune system had not yet joined the fray. Surely they had to know about this by now.

The next thing the erythrocyte observed was that a small group of neutrophils were gathering amidst the herded together E. coli. It seemed like suicide to her. Transfixed AC watched the group of granulocytes then split up, dispersing in the crowd of bacteria without actually fighting them. For some puzzling reason they only seemed to be dodging their attacks. Just what were they planning?

As if on command the neutrophils at the centre then suddenly grabbed or attacked the germs they were among, but not with their blades. They used NETs. She recognized the white mesh, however those weren't as small as the one 4989 had used; these were massive, large enough to cover and bind most of the invading army, two-thirds at least. It almost looked like a blood clot in the end, though unlike red blood cells the germs were struggling against the sticky threads. Even from far away AC could hear them scream, as the mesh cut into them.

Then something hit AC. What about the neutrophils? They were trapped along with the bacteria!

In the meantime, the few remaining germs panicked, caught between the NETs and the ring of other neutrophils and macrophages surrounding them, suddenly finding themselves outnumbered for the first time in this battle. Just like that the tide had turned.

The leucocytes advanced, cutting down their enemies with renewed vigour. But that was not all.

"Move!" A deep male voice bellowed behind her. "Out of the way!"

Startled AC instinctively leaped aside, pressing herself against the nearest wall, just in time. A battalion of black-clad T-Cells ran past her, with them a few more B Cells, probably now equipped with specialized antibodies.

Battle cries were shouted and the lymphocytes finally joined the battle. Despite their intimidating presence, AC felt reassured by their arrival and sighed relieved, letting go of her plait again. Now the E. coli surely stood no chance. This would be over any minute now.

Remaining at the broken endothelium, the erythrocyte watched as the last of the germs were snuffed out by the united forces of immune cells, some of them crying out in fear or pain before being silenced. Though their end was brutal, AC felt no pity, only gladness, even if it was muted with lingering concern, a few of her fingers running over her braided bracelet.

And then it was silent.

To her surprise there were no cheers after the last E. coli were slain. The battle simply seemed to end. Slowly the leucocytes began to tend to their wounded, carrying them off the battlefield, while the macrophages started to collect the dead bacteria, probably to process them; she'd seen their giant pots.

AC hesitated, until she finally left her spot at the wall. She knew she wasn't supposed to leave the blood vessels, but admittedly she didn't care right now and so stepped into the destroyed tissue. Most immune cells simply ignored her and continued their work, others seemed confused by her presence, yet didn't stop her either as she began to search the area.

Eventually more neutrophils arrived at the scene, apparently relieving those who had fought here, which was probably for the best. They all looked so exhausted, all wounded to varying degrees, which did nothing to ease the erythrocyte's mind, her fingers once more feeling over the bracelet.

Slowly the relieved neutrophils left and AC noticed that they seemed downcast, hardly speaking to on another. The implication made her shiver; how many had they lost today?

As she looked around, AC actually spotted U-1146 among those leaving. It was good to finally see a familiar face and she was glad that he too had survived this battle. As the neutrophil walked towards the blood vessel he was suddenly approached by a red-headed erythrocyte, who was ignoring the rules same as AC and apparently offered him a tissue. This had to be AE 3803, his girlfriend; AC remembered that distinct hair curl she could even see from a distance. As AE studied 1146 with a worried gaze, he spoke to her with a reassuring smile, despite looking tired from the long battle.

AC 4293 turned away to continue her own search. He had to be around here somewhere too…

"AC?" At hearing that surprised voice, her haemoglobin leaped into her throat, warmth blossoming in her chest. He'd survived. "What are you doing here?"

She turned around and gasped, as a completely bloodied 4989 joined her on the large chunk of debris she'd used as vantage point. "I…I just had to know." The erythrocyte admitted timidly, a hand clutching her shirt just above her chest. "Are you alright?"

Aside from the cytoplasm, his clothes were torn, but thankfully he didn't seem seriously injured, at least to her inexperienced eyes. For a moment he stared at her, evidently flabbergasted, but then a smile spread across his lips. "…Yeah, yeah; just bruised, nothing serious." He assured her. "I don't think this is any my cytoplasm really. Well, not much anyway…"

AC breathed out relieved, but it was followed by an awkward silence. She hadn't exactly planned this far ahead and he too seemed a bit lost. As she wondered what to say, her eyes returned to the sight near the intestinal wall. "4989? Those neutrophils, what...what did they do? I saw NETs, but there was so much. I thought they were just those little meshes."

He stiffened, his smile faltering immediately. "Wh..what I did was vital NETosis, I just used a bit." The fluffy haired neutrophil explained and patted one of the pockets on his uniform. Then he hesitated for a moment, only continuing reluctantly. "But we can also use more drastic measures as well."

A part of her dreaded to press on, but she wanted to know. "What measures?"

Saddened he looked back to the battlefield and took a deep breath. "NETs are made from our DNA, nuclear or mitochondrial, so if we need to deploy a lot, if there is no other way, we…we can release everything we have."

"Release everything…how?" A part of her could already guess.

A little hesitantly 4989 showed her his bloodied knife. "We either open up our own membrane or allow a pathogen to wound us, often we'll grapple one of our targets too, using ourselves and our NET to trap and kill the germs. It's called suicidal NETosis."

Suicidal NETosis

There are two versions of NETosis. During vital NETosis the neutrophil quickly releases a vesicle containing the mesh, leaving their membrane intact, allowing the leucocyte to continue phagocytising microbes.

During suicidal NETosis however the neutrophil's membrane ruptures, realising a large amount of chromatin-mesh, killing the immune cell. This can take hours, compared to vital NETosis, due to the extensive intracellular NET formation.

Both are activated via different pathways.

AC's eyes widened. "They sacraficed themselves." She breathed horrified.

4989 gluped and nodded. "Yes." Quickly he put the blade away, trying to muster a brave smile, but struggled, making it look brittle, even sorrowful instead. His eyes shimmered. "We're neutrophils; eventually we die fighting and before we let pathogens wreak havoc in the body, we rather take them down with us. That's our function."

"So you,…you would do that too." Her haemoglobin seemed to be twisting itself inside her chest at that thought, her cytoplasm apparently now replaced with something much colder.

There was a moment of hesitation, his voice low when he replied. "Yeah."

"Oh." Was all she managed to utter weakly.

He rubbed the back of his head. "It's not like I want to, I don't think any of us do, it's really more of desperate last-ditch effort. But if there really was no other way…" 4989 broke off, giving her a meaningful look as he bit down on his lower lip.

There was heavy silence following his words. At first AC could only stare until suddenly she just wrapped her arms around him.. She didn't know what to say. What could she say? Stay safe? Be careful? They sounded awful in her head, how much worse would they sound out loud? She didn't want him to die, especially not by his own hand. And after what happened to FP 1564…immediately she hugged him a little tighter, fingers digging into his uniform, leaving her standing on her toes. No, not him too.

But she had also noticed something else as well, making her remember something he'd told her the day FP had died. "Daily some of us die to protect this body. Some of them friends." She didn't know whether the ones who had sacrificed themselves today had been his friends, or even if he'd known them, yet she could still see how much their deaths affected him. AC had never seen him so sorrowful, so hurt.

And so AC 4293 just embraced him. She may only have known him for a while, but that didn't matter; she cared about him.

"AC?" He sounded so unsure, almost confused. Admittedly so far he'd been the one to hug her and she'd merely accepted the gesture, let him hold her closely as he consoled her.

This was the first time she hugged him and her cheeks flushed a little at that thought. "You were there for me when I needed it the most. What kind of friend would I be if I wasn't there for you?" AC had made up her mind; no matter what he thought, she did consider him a friend.

At first she got no reaction, as if he had frozen, until suddenly his arms were around her, squeezing her gently.

...

"You sure you don't need any first aid, Hakkekkyū-san?"

Slowly 1146 shook his head. "I assure you, I'm fine, Sekkekkyū. All I require are some fresh clothes and some rest." He mustered a smile. "You really mustn't worry."

She sighed. "That's easier said than done." The red haired erythrocyte told him as they walked together back to the blood vessel. "Want me to get you a tea, maybe something to eat while you clean up?" Always eager to help; it was something he loved about her.

And her offer did sound good. "I'd appreciate it, thanks." He told her calmly, feeling quite exhausted now that the rush he'd experienced during the battle had worn off.

AE 3803 smiled happily at that, the sight warming his mitochondria, and she grasped his wrist, apparently not caring that she got cytoplasm on her gloves, gently pulling him further. She'd never been deterred by his bloodied appearance after each battle, always first and foremost concerned for his wellbeing. If she could, she would move heaven and earth to make sure he was alright, of that he had no doubt.

1146 truly felt lucky to have her in his life, especially on days like this. Immune cells, most notably neutrophils died to defend this body and all living within, but so many intentionally sacrificing themselves undeniably weight upon him. One day he too might have to do the same, and AE 3803 was aware of that. And yet she'd decided not to leave him, for which he would be eternally grateful.

Together they continued to make their way across the field of debris, until something caught 1146's eye. Not far from them was one of his friend, but he wasn't alone either. He stopped, much to AE's confusion and nodded once towards his fellow neutrophil.

"Oh." She gasped surprised, a hand on her lips and 1146 suppressed a small chuckle.

U-4989 was being trapped in a tight embrace by the very erythrocyte he was trying so hard to befriend, hugging her in return. But it was his expression that amused the other white blood cell so much.

The fluffy haired neutrophil had always been one to openly show his emotions at any given time; he remembered 4989 breaking into tears when he had believed 1146 was about to die that day in the stomach and AE 3803 had mentioned that he'd cried upon learning how highly she thought of white blood cells, literally touched to tears. So seeing him cry a little now after all that had happened today wasn't that surprising. However when the two neutrophils made eye-contact 1146 also saw elation in those wide, grey eyes, before 4989 silently mouthed. "She's hugging me!" He seemed positively exhilarated.

AE 3803, who naturally had seen that as well giggled and gave an equally silent thumbs-up, while 1146 merely nodded, happy for his friend.

...

It was strange. AC 4293 had never been one to shy away from physical contact, but it surprised her just how comfortable she felt hugging 4989. Then again, given all that he'd done for her and just the way he was, it was so simple to be at ease around him.

Frankly she could have stayed a little longer in their snug embrace, when she picked up on something. "Are you crying?" The erythrocyte quietly asked, her voice a whisper.

She could have sworn she heard a sniff. "…no?"

AC smiled; he really could be so adorable. "I won't tell." She assured him, arms still around his neck, a hand stroking soothingly over his back.

Suddenly he rearranged his hold however and the erythrocyte felt him lift her up. Before she knew what was happening, 4989 started spinning, swinging her around in circles and AC laughed, closing her eyes in an attempt not to get dizzy. She hadn't been sure how he would react to her considering him a friend, but this reaction was better than anything she could have hoped for.

Eventually he stopped to put her back down on her feet again, still swaying a little himself. "Ouch." AC suddenly flinched as soon as she touched the ground; she'd completely forgotten about her injury for a moment.

Alarmed the neutrophil scanned her body. "Are you alright?"

She nodded, but lifted her foot, rubbing it carefully. "Another erythrocyte hit my foot with his cart while he was on the run. Nothing serious, it just hurts." However as soon as she'd finished her sentence, AC felt herself being lifted up again. This time he supported her back with one arm, while the other had found its way under her legs. "What are you doing?"

"Carrying you, obviously." 4989 told her, lips curving into a smile once more, though his eyes were still glinting from his tears. "You can't walk like this, not until someone's taken a look at your foot."

AC opened her mouth to reply something, but then chuckled amused. It really was sweet of him. "You're going to insist, aren't you?"

His smile turned into a grin, his big eyes now looking at her brightly. "Yep." But then he noticed something else. "Oh, I think I got some cytoplasm on you."

"What?" Momentarily confused by his suddenly sheepish expression, AC looked down. He was right, there was a lot on her jacket and shirt now, even her shorts had not been spared. "Ah; my bad." She'd been the one to hug him in the first place after all.

"Guess that means another visit to the wash station for you then." He noted.

The auburn haired erythrocyte shrugged and smiled, readjusting her arms so they settled around his neck once again; there wasn't a better place to hold onto really. "It's okay. Besides, now I got a chance at a rematch." That promised to be fun.

And if his bright smile was anything to go by he had no objections either. "You're on."