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View submission: Ask Anything Wednesday - Engineering, Mathematics, Computer Science
This is a super complex subject that I'm not qualified to explain in any sort of depth, but to get this down to the most basic level, part of the process works like this:
Certain immune cells (B cells) undergo extremely high levels of genetic mutation/reshuffling (somatic hypermutation) in the part of their DNA that produces antibodies. Antibodies stick to other molecules, but exactly *what* molecule they stick to depends on their structure, which depends on the DNA that produced them. Also it's worth noting here that the antibodies sit on the surface of the B cell at this point, they aren't being emitted into the body yet.
So what you have is a huge number of B cells, all of which are randomly mutated to produce unique different antibodies that stick to different things. Since there are so many of them, some of them are bound to stick to just about any kind of protein or big molecule they come across.
Your body then weeds out the B cells that produce antibodies that stick to the molecules that are normally floating around in your body, the "self" molecules. If it doesn't do this properly, you get an autoimmune disease. If you have any sort of foreign proteins/substances in your blood (like from, say, a virus or bacteria) then other immune cells will start grabbing those up and showing them to B cells. Because there are so many B cells with so many random receptors, at least *some* will latch on to this substance.
Once a B cell has latched on to a substance, it starts multiplying and, after more complex stuff I'm not describing here, eventually you have a bunch of B cells descended from that one which all produce antibodies similar to that original one that latched on to the substance. Those antibodies can not only directly interfere with the function of a virus or bacteria, they can also flag cells infected by it for destruction.
And this is just talking about B cell immunity!
But anyway, to TL;DR it: 1) each immune cell attacks a random specific substance 2) immune cells that happen to attack your own substances are eliminated by the body 3) when some pathogen invades you, immune cells that happen to attack it multiply in response
Really it's more akin to natural selection than thought. A beetle doesn't think "I need to grow these wings to get better adapted to my environment", instead it's the beetles with the right wings that survive and multiply. Similarly, the immune system cells don't think "that's a pathogen, I need to make this receptor to attack it" instead the cells that do the best job of attacking multiply.
Comment by cburgess7 at 09/03/2022 at 20:00 UTC
0 upvotes, 0 direct replies
This is incredibly informative. Thank you.