How do macrophages know what to eat?

Axel Boldt axel at uni-paderborn.de
Thu Feb 12 00:12:30 EST 1998


Hi,

I've asked this question here before, I didn't quite understand the
answers, was advised to read a good immunology book and did just
that. However, every book I get my fingers on seems to gloss over the
(from my perspective) most important point about the whole immune
system.

Neither B- nor T-cells nor anybody else will take any action unless a
new antigen has been engulfed, processed and presented by a macrophage
(let's talk about thymus-dependant antigens only for now); so the most
central question of all should be: how do macrophages know what to
engulf? Which soluble proteins, which free viruses, which bacteria?
How do THEY distinguish self from non-self?  And, given this huge
evolutionary pressure, why are there not more pathogens who can
circumvent this macrophage detection mechanism and thereby bypass the
whole immune defense? Why does everybody talk about the wonders of
gene rearrangement and somatic mutation which account for the
specificity of antibody, when the genes that tell macrophages what to
do are much more important?

Thanks for any reply that could help clear this up for me.

Cheers,
  Axel



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