Why does chronic inflammation impair immunity?

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Inflammation is an immune response, so if someone experiences chronic inflammation (ie chronic activation of the immune system) shouldn’t they have more reactive immunity?

Everything I can find just says that chronic inflammation can cause “a breakdown of immune tolerance”. BUT WHY??

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Anonymous 0 Comments

What you’re reading about breakdown of immune *tolerance* fits with your intuition, which is also correct. Immune tolerance is the process/concept by which elements of the immune system do recognize or interact with an antigen but actively don’t respond to it with aggressive immunity. This is the case for many innocuous antigens, and when it isn’t, we start talking about allergy.

Now, like many things about immune function, tolerance is not fully understood. However, the context in which cells of the immune system encounter antigens, especially for the first time, matters for how they respond. If they’re surrounded by inflammatory signaling, as is going to be the case in chronic inflammatory disease, it skews their “decision making” away from tolerance and can even damage existing tolerance — that’s usually what we mean by *breakdown*, specifically.

That said, there’s also the concept of anergy, which is when immune cells receive persistent low-intensity activation cues but aren’t really made to fully pull the trigger, or are specifically given inhibitory signals. That’s typically more of a thing in B/T cell activation though, at least as I understand it. You’ll often find anergic T cells around tumors (expressing CTLA-4/PDL-1), for example.

Source: MSc immunology

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