Imagine our organism as a nation (an extremely crowded one,
with about one hundred thousand billion cells, viz. the citizens):
a nation bounded by long borders, with checkpoints & barracks, and policemen
and soldiers everywhere to maintain public order and drive away enemies, lurking continuously.
It is a complex nation crisscrossed by a massive number of rivers and canals, hyper-technological, but with (very advanced) systems still partly to be decrypted. Follow our illustrated stories, and we will tell you how people live in this strange, cruel and almost perfect place.
All true, yet all so unexpected.
How can you keep a complex body like ours under control 24 hours a day,
where bacteria and viruses are constantly trying to get in and where
internal gangs of "rebels" (cancer cells) are also at work?
The first to intervene are the officers from the Enemy-Eater Department
They move along blood vessels, silent, fast, frightening. Meeting them is scary if you don't have what it takes. The Enemy-Eating Squad are trained to help – at any time of day or night – colleagues in other units of the Security Forces, who are constantly searching for hidden intruders: a very difficult operation in an overpopulated organism with a hundred billion cells. There are enemies that try to get in through the long borders and hide, but there are also billions of illegal immigrants, who are tolerated if they offer useful services to the body, like the slave bacteria of the intestine (but they require close surveillance, in any case). These agents also have to deal with rebel groups, namely the cancer cells, that every now and again attempt to set up their own state within the nation. In short, it's extremely difficult to keep order in our body and the National Defence System has to employ huge resources to make sure everything goes smoothly, and the enemies/illegal immigrants/rebels don't take control.
What kind of country is our body? Not a democracy, that’s for sure, but not a dictatorship either. It's a state where the laws were decided thousands of years ago and are still valid. Everyone knows them, and everyone applies them, without thinking (even if mutinies occur from time to time, and you get these rebels – the cancer cells, to be exact -, which are often extremely dangerous. It is true too that, the military sometimes make mistakes, potentially doing even more damage). But, as a rule, every cell of the body knows exactly what it has to do and doesn’t contest the orders it gets instantly, even if some of these "instructions" may seem unfair: for example, the front-line soldiers, who fight in close combat against the most dangerous enemies, must often commit suicide once they’ve accomplished their mission (even successfully), because this is what the ancient laws established. And no one protests.
Agents often have to commit suicide, even if they have worked bravely.
It's the rule
Our body is a high-tech nation, even if certain aspects sometimes seem unfathomable. Communications, for example, take place via a very sophisticated network of thin electric cables that reach into the remotest areas, or via briefcases (hormones, alarm molecules, and others) released into the (very thick) blood vessels in every region. Thanks to a system that our brain would not have the faintest idea how to design, each case has a series of codes for ‘the eyes only’ of the recipient, which recognizes and picks it up as soon as it ‘meets it’. Obviously, errors may occur, as billions of cases are circulating in the blood at every single moment of the day. But this dispatch system works very well as a rule, and makes those we are accustomed to outside pale in comparison. It is possible that some error occurs. But the system normally works very well
Here are two briefcases addressed to the Enemy-Eating Squad: more specifically, MonoCell agents on patrol. The briefcases have been released into blood by forces who are grappling with a commando of unidentified enemies in a nearby area.
The body is made up of a long series of "buildings" without windows and without house numbers, running along the blood vessels, but Enemy-Eating agents have no problem understanding where the colleagues who have asked for help are: the instructions in the briefcases contain a kind of chemical trace, which makes it easy to find the right place. The security forces have a licence to kill aggressors, or deserters, immediately, without investigations or trials (there are no Prosecutors or Courts in our body): the nation’s ancient laws allow for this, and everything must be done as quickly as possible.
The agents move quickly up to the spot the alarm signals were sent from: there’s the usual bustle of cells, agents and briefcases all around, in a flow that appears chaotic only to those who don’t know very well how our body works. To reach colleagues engaged in the fight against the enemy, the MonoCell agents use substances that literally soften the blood vessel walls. This makes it easy to open up a breach, which will then be quickly repaired by the Maintenance Service. The agents are now inside the infected site. Corridors, stairs, inner channels: it’s a labyrinth where it’s easy to hide, for illegal immigrants. But the agents swarm in, and they’re aggressive. They don't know who the enemies are exactly or what they've done that's dangerous, but that's not their business. Their mission is simple: kill on sight any individuals unable to show a passport issued by our body. The battle is about to commence: they are very close, and really scary. Entering the buildings is easy, even if there are no doors and house numbers
The agents activate the M Function (another technological marvel, designed thousands of years ago and still used today) to boost their strength: their body is transformed instantly, losing its rounded shape, and creating extensions to envelop the enemies and kill them. As in a dark fairy tale, the MonoCell cops transmute, right in front of their stunned opponents and they become BigMouth agents. They approach the enemies, quickly scan their passport codes, and decide instantly whether to kill them. But, at the same time, they throw new cases into the river to call for more backup: the Special Troops. Unlike the BigMouth, these forces can tell the enemies apart and they know them by name. Meanwhile, they launch new briefcases into the river to bring in special troops
The BigMouth agents don't waste any time, they eat, in the real sense of the word, any enemies that present an irregular passport. The mouth expands immeasurably, the victim is swallowed, then engulfed, still alive, in a special capsule inside the agent's body: this is what the law enforcement calls the "death chamber". Corrosive and digestive fluids then flood the capsule. The enemy is dissolved in a matter of seconds (without the BigMouth being damaged), and digested by the agent itself. The military almost always win. If they don’t, very serious trouble could put the body in danger.
Once they’ve eaten an enemy, the BigMouth display its passport number on their suits (along with their police codes, to avoid misunderstandings or any confusion, and so they are mistaken for the enemy). Why are they doing this? To draw the Special Troops' attention to that particular enemy and its fellow foes, and to make the defences even more efficient, for the future. Everything has been planned, as much as possible, to maintain order in the nation-body. After killing the enemy, the agents expose their passport numbers
The story you’ve just read is all about what's really going on inside us. The characters in this first episode are monocytes (Enemy-Eating MonoCell agents), our organism’s critical guardians. They continuously patrol the blood vessels, looking for potential enemies (and they might get a bit rough at times!) anche se un po’ rozzi. Better still, they look out for signals sent by other cops/guardians who are inside organs and related tissues, and grappling with more or less dangerous enemies (viruses, bacteria and other). NB: there are very few enemies that dare to come out into the open and swim in the blood for a long time.
When patrolling monocytes detect the alarm signals [chemokines: briefcases] thrown by their colleagues into the rivers, they immediately head for area of the body the calls for help came from. To get inside, they use a special technique to make a hole in the capillary vessel walls (which sometimes makes liquid ooze in or out, and this creates a swelling, or edema]. As soon they arrive at the spot where the enemies are holed up, the monocytes transform (physically, in an almost magical natural process) into a more aggressive type of soldier: the macrophage (which we called BigMouth), which devours the enemy [or foreign substances: tar from cigarettes, for example].
But this is not enough: the macrophages emit alarm signals to get the attention of the elite police force: the lymphocytes. What are these alarm signals? They are proteins in the enemies [bacteria] that macrophages eat and "digest". These proteins are displayed on the suit [outer wall] of the macrophages themselves, and become a warning signal for B and T lymphocytes, which are able to detect them. The macrophages also add a particular series of molecules to their suit which act as "ID cards" (the Police badge, etc.) and are called MHC (Major Histocompatibility Complex). These determine the blood groups. If the lymphocytes don’t find the right MHC, they destroy the macrophage even if it is part of the Army and not an enemy (but it has an enemy protein on its back).
Concept and text by Paolo Rossi Castelli | drawings by Marino Neri | scientific consulting by Annamaria Castellazzi | web development by MaskeDesign
You are reading
Along the river, on a mission to hunt down our invisible enemies Where we are: inside the strange nation that is the human body.
Who are the characters in this episode: officers from the Enemy-Eater Department (monocytes/macrophages, to use the scientific term)
What they do: they collect alarm signals sent by other officers in the great National Defence System (the immune system) and mobilise to, literally, eat our enemies.