Hi guys!
I just had a few questions to ask.
Are pathogens recognised as foreign by the absence of self markers or by the presence of non-self markers?
Presence of non self markers - antigens. However the absence of a self marker (such as MHC) can also cause an immune response against that cell.
Also, is it correct to say that virions are non-cellular pathogens?
Yep.
Just to confirm, are antigens molecules that are recognised as foreign by the immune cells? Are antigens non-self markers?
Sort of. Antigens are molceules that trigger the production of antibodies - this
should mean that they're all non-self, but in the case of things like an auto-immune response, an antigen can be a self molecule.
When describing the steps of the immune response, what the main points we should include because in some sources there is more detail while in other details they don't say that a fever is caused when macrophages secrete interleukins for example?
Thank you for your help.
It depends what part of the immune response you're talking about - you can have a flick through past exam answers and see what they've considered important.
Humoral:
- Naive B cell binds to free antigen
- T helper cell binds to identical antigen presented on MHC2
- T helper cell releases cytokines that cause proliferation and differentiation of both B and Th cells.
- Memory cells stick around, B plasma cells produce heaps of antibodies complementary to the antigen.
Cell-mediated:
- Cytotoxic T cell binds to antigen presented on MHC1.
- Releases granzymes and perforins that kill the cell
- Divides and differentiates and goes around killing other cells presenting identical antigen fragments.
- Maybe mention that cytokines released from T helper cells help with the Tc cell proliferating and differentiating, but also might not need to mention that.
^They're just the rough points, you should write out the ideas properly, but that's the important bits.