The way I understood immune system is that:

  • phagocytes detect viruses and present it on their surface and become antigen presenting cells.
  • Then, T-helper cells try to bind to these phagocytes that have antigen on their surface and found, T-helper cells become effector T-helper cells which then cause the activation of B-cell.

Question 1: If phagocytes can't detect virus, that means T-helper cells wouldn't be activated(there would be no process of cytokines) and if no cytokines, B-cell activation wouldn't happen. and if no B-cell activation, no antibodies releasing. So This means unless phagocytes detect the virus, B-cell activation doesn't happen, but this would be too bad, because if B-cell activation depend on the phagocytes finding the virus, this means if innate immune response fails, adaptive also fails. I'm wondering when would still B-cell be activated even without phagocytes finding the virus in the first place ? otherwise, B-cell always depending on phagocytes would be too bad...

Question 2: Am I right that B-cells can detect/identify the virus that couldn't have been identified by the phagocytes ? I think so, because phagocytes have general PRR which sometimes might be unable to detect, but B-cells have more combinations of variable portion proteins that could detect more stuff ?

  • $\begingroup$ B cells can be phagocytic, and can present antigen to T cells both via MHC-I and MHC-II pathways. Different PRRs can be found in many cell types so they can detect infection and signal that to the immune system. You might be interested in the topic of immune evasion. $\endgroup$
    – MattDMo
    Commented Nov 21, 2022 at 20:10
  • $\begingroup$ Thanks for the answer. But am I right about my 2nd question ? $\endgroup$ Commented Nov 21, 2022 at 20:54


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