On: Adult immune systems ‘remember’ germs to which the...

[nullc]

> But why doesn't the larger keychain also increase the chances of auto-immune diseases, when they happen to fit our own locks?

The process that generates immune cells tests them for autoimmune reactivity and aggressively culls ones that are.

[nomel → nullc]

Could you provide the name for this, or something I could search for? This is fascinating.

[rcthompson → nomel]

Look up the function of the thymus in T-cell development and selection.

https://en.wikipedia.org/wiki/Thymus#Function

[alextheparrot → nomel]

The term is "Central Tolerance".

The Thymus (Which someone else mentioned) effectively checks the following:

(1) Does the cell react to an antigen (Foreign particle) [β-selection]

(2) Does the cell still work with the immune system (Can it bind to the cells it needs to bind to once it finds the antigen) [Positive Selection]

(3) Does the cell recognize only foreign particles and not the body itself [Central Tolerance / Negative Selection]

[mirimir → nullc]

Sure, but it doesn't always work :(

I had the misfortune of blowing out my right knee and acquiring a chlamydia infection ~simultaneously. And then developed acute rheumatoid arthritis. Which has progressed, albeit slowly, ever since.

So it goes.