Except that almost every cell is somehow related to immunity. Almost every cell in the body has MHC Class I which constantly presents a subset/signature of its proteome to the immune system in case it gets infected by a virus, etc. Cells that don't do this are deleted by Natural Killer cells.
Also, many immune factors that people thought were restricted to particular compartments or cell types have been found in "non-immune" cells. For example, complement protein was thought to be a blood factor that is only made in the liver, but it turns out that it is also made locally by stromal cells of the intestine:
Not to mention the burgeoning field of neuroimmunology - there are neurons in the spleen which are in direct contact with macrophages and we don't know why (or at least didn't know why a few years ago when I learned about it). But avoiding people with disease symptoms could be considered part of the 'immune system.'
I can follow what you are saying because of what I learned in the book Immune by Philipp Dettmer, which I highly recommend for a popular-level introduction to the complexities of the immune system. The whole bit about the "presentation windows" that cells use to communicate if they are infected, and how some viruses try to fight that by not presenting anything, and how the immune system tries to fight _that_ by deleting cells that don't present anything... fascinating stuff!
Another example of how almost any cell contributes to immunity is that depending on the way a cell dies (apoptosis vs pyroptosis vs necroptosis), it can release its contents, including nuclear proteins, and other "Damage-associated molecular patterns" which act as an inflammatory recruiter of other immune cells.
For pyroptosis this includes endothelial cells, epithelial cells, neurons, heart muscle cells, liver cells, fibroblasts, and pancreatic β-cells.
On top of this, there are several ways that "non-immune" cells are constantly doing internal immune tasks, or performing 'citizens arrests' if you will, including: restriction factors, cellular stress response, autophagy, and viral RNA/DNA detection. For example, many "non-immune" cells express Toll-like receptors which are used to detect "Pathogen-associated molecular patterns".
There is also a similar anime/manga called "Cells at Work! Code Black" which deals with an unhealthy individual. It is not nearly as fun to watch as the original, due to what the human's body experiences, but it's still as educational as the original.
Well, it's not quite 1:1, but the difference is only about one order of magnitude...the average military spending seems to be about 6-7% of federal budget, and the average federal income tax rate seems to be about 25%, so about 1.5-1.8% of taxable income worldwide is going to defense. I am hugely back-of-enveloping of course, but it IS also apparently the case that military spending is about 2.2% of GDP on average. So, again, only about one order of magnitude by a second measure.
We might say this suggests that our bodies are about an order of magnitude more efficient and/or civilized than our societies, which seems conservative if anything, no?
This might be a translation mishap. The Spanish word "billón" translates to "trillion", and the English word "billion" actually translates to "mil millones" (a thousand million). https://en.wikipedia.org/wiki/Billion
Yet our cultures seem resistant to usage like "1.8 teracells". Is it too nerdy? Would it be more palatable to normies if each prefix had a cardinality suffix ("teraion" is not great...)
The article opens with that: "For the first time, a study has measured the size of the immune system: if it were an organ, it would weigh more than a kilo and represents 0.2% of all human cells"
Or maybe a relative scale. 1.8T cells dedicated to defending, compared to X cells dedicated to defecating, or Y cells dedicated to digesting.
All joking aside, National Geographic says there's about 37 trillion cells in a 70 kg (154 pounds) human body. So that'd mean 5% of those are dedicated to defending.
I think this is probably an underestimate, given the existence of a lot of the maturation, immune recruitment and immune cell genesis happens within specialized organs (the spleen, bone marrow, thymus, and lymph nodes). Of course, it depends what you consider a system.
The immmune system is so incredibly complex and it's quite amazing how it works.
If you are just a little bit interested i highly recommend the book "Immune: A Journey into the Mysterious System That Keeps You Alive" by Philipp Dettmer, the creator of Kurzgesagt.
It's a really fun book to read and learn about your immune system.
I am having trouble following what is being counted here. Is it just cells that seem to be devoted to fighting off foreign threats? Or all cells in a system that has an immunity function?
For example: it counts 'blood cells'. But does that count all blood cells, or just those that fight disease like white blood cells?
It would be interesting to try to draw parallels with other complex systems.
e.g. Is the percentage of mass or resource allocation to a body's immune system similar to that devoted to a nation state's military and police force? Do all complex systems naturally normalize on a similar percentage devoted to defense that maximizes resources going to non defense productivity without leaving the system too vulnerable to attack?
On a lighter (or perhaps much darker) note, that makes me think of this exchange where a wizard-detective is trying to convince a mundane coroner that vampires exist.
> "Maybe," he said. "But I don't see how things that hunt and kill human beings could be there among us without our knowing."
> [...] "You can check with the FBI. That's out of about three hundred million, total population. That breaks down to about one person in three hundred and twenty-five vanishing. Every year. It's been almost twenty years since you graduated? So that would mean that between forty and fifty people in your class are gone. Just gone. No one knows where they are."
> Butters shifted uncomfortably in his seat. "So?"
> [...] I let the silence stretch for a minute, just to make the point. Then I started up again. "Maybe it's a coincidence, but it's almost the same loss ratio experienced by herd animals on the African savannah to large predators."
-- Dead Beat by Jim Butcher
No clue if the math works out. It took me a while to find it, I kept thinking it was from one of the Blade movies instead.
And to crudely compare mass to resource allocation, the article claims more than 1.2kg of immune mass for the 73kg model individual, or 1.6% of total mass. The US military budget is about 3% of GDP.
The resource devotion of most all nation states seems to settle in this 1-3% range, excluding those with more active security tensions. Ukraine for example running an absolute fever at 34% and Israel chronically stressed at 4.5%. https://en.wikipedia.org/wiki/List_of_countries_by_military_...
The middle east in general seems to over allocate on their immune system. This would actually align with what I've been reading recently that modern Islamic culture is much more of a physical might makes right system. And that overspend on aggression and displays of power is part of what hampers their economic vitality while the more peace loving west gets to devote more resources to non destructive pursuits. Turning the other cheek and meeting in the middle is seen as weakness in the Middle East, but it counter intuitively is the reason that the west is the stronger system.
Similarly, those who get their vaccines spend less time sick with their immune system inflamed, and so get to be more productive at work or athletic pursuits and compete better than those that abstain.
Edit: one of the core functions of the immune system is identifying and eliminating pre-cancerous cells from your own body, if you downvote this out of reflexive politics you are a clown.
> if you downvote this out of reflexive politics you are a clown
It is not that serious... The emphasis that you yourself added is counterproductive to your point and deliberately precludes discussing viewpoints that would be valid because nobody wants to deal with a "hyper-reactive".
> And that overspend on aggression and displays of power is part of what hampers their economic vitality while the more peace loving west gets to devote more resources to non destructive pursuits.
I'm sure this has nothing to do with centuries of western imperialism in that region.
I'd be (non-sarcastically) interested in reading any materials/sources you have on this specific topic. Is this view simply because dumping on the west is popular nowadays, or are there really strong ties on islamic culture and its relationship with the west?
It is unusually well-funded, and also large in absolute numbers, but not proportionally to the population. Greece and South Korea, for instance, have 1.3% and 1.1% of their populations in active service.
When you include reservists (of varying quality) the cake goes to North Korea with 30% (!), but notably also Cuba (11%), Taiwan (7.8%), Israel (7.6%).
During WWII, many nations managed to cumulatively mobilize 10-15% of their population (about 9%, 16 million, for the USA).
Not propotionally, no. The US comes 77th out of 150 or so countries in number of active military personnel per capita. Small countries with an existential threat looming over them like the two Koreas and Cuba have unusually large militaries compared to their size.
The US is the third most populous country so its military is still exceptionally big in absolute terms.
No. Rather, it's that many other countries are benefitting the US-led global peace since WW2 such that they can afford to keep unusually small militaries compared to historical norms. Pre-modern states spent way more on defense, and that is what would happen if US dominance weakens and large wars become plausible again.
I get where you're coming from, considering the many smaller and proxy wars that the U.S. has involved itself in since WWII but the point of the other comment is also true to a great extent:
First, if you think Stalin wouldn't have taken his armies right to the Atlantic coast of France after crushing the Nazis, you'd be badly mistaken. It was specifically U.S. military power (and the atomic bomb) that stopped him from trying this. The rest of the allied powers were too exhausted and small to be credible deterrents.
After that, over the following decades on multiple occasions, the same thing applied, a major power, like the USSR or China was tacitly or openly stopped from taking things further or attacking more specifically because of US presence in the background. This applies to South Korea for sure, but also to many places in central Europe and elsewhere.
Today, the U.S. remains as the biggest deterrent of further Russian encroachment into places aside from those that it specifically considers its rightful domains (Ukraine, for example, where even foreign threats of retaliation couldn't stop a nationalistic sense of having the right to attack). I'd argue that this is one of the major reasons why Finland wasn't invaded long ago. (U.S. presence and the dawning realization among the Russian leadership that its supposedly strong remodernized military is much shittier, weaker and more corrupt than it was "supposed" to be.)
The US military is unusually large, but that's primarily because the US economy is unusually large.
The US does spend more than average, but we're talking 3.5% vs the global average of 2.2% of GDP. So, the overwhelming might of the US military isn't because Americans are rapid warmongers, but because the US economy is the most productive per capita of all large countries by a massive margin.
My first thought was how software complexity imitates life.
I remember seeing a reference[1] that about 5-10% of all Windows operating system source code was dedicated to security in one sense or another, such as malware detection, cryptographic libraries, certificates, Defender, Bitlocker, UAC, all the complicated code for file permissions, privileges, authentication, etc.
[1] This is one of those things that is very difficult to Google for, and I haven't been able to find a reference to where I read it.
The first couple google results suggest that there are about 38 trillion human cells in the average male adult, plus about as many bacterial cells. Estimates vary a bit, but at least the human cell count should be accurate to within 10 trillion.
So estimating at 80 trillion cells per human, that puts our "defense spending" at around 2.2%, quite similar to nation state budgets.
> Most of the relevant data available in the literature were not stratified by sex and age, and thus, our estimates of the number of cells per gram of tissue mass (henceforth “cell density”) represent a broad normal range independent of sex and age. We use the cell density estimates to extrapolate our results to other segments of the population based on the reference mass of their tissues and organs (11). Thus we obtain a reference estimate for the immune cell population of healthy adult females weighing 60 kg and reference children of age 10 weighing 32 kg (11).
I don't agree with the idea of describing some stuff as an 'immune system'.
Blood system, digestive system etc - yes, I can see those, or test for their physical existence. But the 'immune system' is just a concept, not actually a system of the same type as the others. It's a abuse of the term 'system' as it is typically used to describe a coherent and related set of anatomical 'bits'.
What's funny is that I think you're right but in the wrong direction. All of these individual systems are made up differences because they are inter-dependent.
If you think about a house, you can say you have a plumbing system, or an electric system. You can also say you have a 'comfort system' or a 'support system'. Its same use of 'system' but its a totally made up idea, nowhere to be seen.
So, in the body, you can see a digestive system, lymph system, etc. But there is no 'immune system' - its just an idea. Its a label without something to be assigned to.
Well, we live in the microbes' world. So I would argue that your entire body is your immune system, including the part of your brain which doesn't like the smell of poop.
On the adaptive immune system, this is a fun read:
But why describe 'the body' as an immune system, when the description refers to nothing in particular (unlike the lymph or digestive systems)? The body has many elements that are nothing to do with health and fighting disease - not everything is 'immune system'.
When you say "we live in a microbes world" this indicates one way to look at things. You can also approach things from different perspectives - eg engineering, chemistry, physics, politics, philosophy, etc - there are many approaches to any part of reality. While a different perspective might give an interesting angle, you do see that the underlying reality of 'the body' has not changed? And that it is a misuse of language to say and treat something is a physical thing, when it cannot be pointed at?
Making a term ('the immune system') broad and refusing to use an existing term ('the body') is, to me, a sort of trick to conjure something into an imaginary existence. To me, you are not saying something meaningful if you say 'the body' is 'the immune system'. Whereas you are saying something meaningful when you point at guts etc, and say 'this is the digestive system'.
The digestive system has form (guts etc) and function (extracting energy from food). I can point at it.
This is not the case with the immune system, because this 'system' is just an idea. It cannot be pointed at or isolated, like other bodily systems. And yet it is treated as if it is real, but where is it?
You might as well use 'the body' as a term, rather than 'immune system' - the term is so broad, it is meaningless to me.
There are different parts (often not physically connected, but connected via chemical signalling) which work together to perform various functions. If one of the parts doesn't work, the function is degraded. It's a distributed system.
Also, many immune factors that people thought were restricted to particular compartments or cell types have been found in "non-immune" cells. For example, complement protein was thought to be a blood factor that is only made in the liver, but it turns out that it is also made locally by stromal cells of the intestine:
https://www.biorxiv.org/content/10.1101/2023.02.02.523770v1....
Not to mention the burgeoning field of neuroimmunology - there are neurons in the spleen which are in direct contact with macrophages and we don't know why (or at least didn't know why a few years ago when I learned about it). But avoiding people with disease symptoms could be considered part of the 'immune system.'