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August 17

Is it possible any of the 100 billion humans has acquired infection resistance for too many things?

Or at least someone in contrived future scenario when you can 3D-print any wild or invented germ you want dead, live or weakened and be acquiring many immunities at once at all times till you're 100 years old?

What would happen if you try to make the immune system remember too many things? The blood gets thick with antibodies and memory cells? Number of memory thingies in body level off before they cause serious problems, at the cost of reducing the effectiveness of some acquired immunities or losing some entirely? Which memory thingies get reduced first? Those for mild or easy to fight germs?Ones that haven't been used in a long time? Everything reduced equally? Protections are cut in some sort of suboptimal pecking order? (like how Jenner's cowpox was temporary but you'll never get the sane exact cold again?) Protections are cut at random?

2. How many new germs can the immune system learn at once? If it's not numerous enough then it may not be arithmetically possible for even a 130 year old immune system to have seen too many strains. Sagittarian Milky Way (talk) 17:23, 17 August 2020 (UTC)[reply]

While memory B cells can survive for a long time, they do not survive forever. The mass of an antibody (an immunoglobulin molecule) is about 250×10⁻²⁴ kg. A ballpark figure for the total mass of the red blood cells in the human body is 540×10⁻⁶ kg. That leaves room for an awful lot of antibodies before they begin to contribute significantly to the protein content of the blood. --Lambiam 07:47, 18 August 2020 (UTC)[reply]

Animals such as goats and deer, that go foraging around and eating garbage and stuff, have ridiculously powerful immune systems. Maybe even more for scavengers, bats, etc. I do wonder how much it affects their general health. Like if you have that much learned immunity going on, maybe it can make you more prone to autoimmune disorders? I know it is possible to acquire allergies, which are basically false-alarm immune responses. 2602:24A:DE47:BB20:50DE:F402:42A6:A17D (talk) 08:35, 19 August 2020 (UTC)[reply]

It's worth considering that other animals can have different strategies for immune response and protecting against infection. Bats, for example, don't do much of an inflammation response to viruses, and use different antiviral strategies to us. These strategies result in viruses evolving to counter them, including needing faster cell to cell transmission rates. SARS-CoV-2 likely evolved many of its properties that are so dangerous to us as a response to bat immune response. --OuroborosCobra (talk) 19:02, 20 August 2020 (UTC)[reply]