Hi, I'm really confused about the concept of antigens and b lymphocytes as well as t lymphocytes and I'm struggling with a definition for antigens because they can't initiate an immune response because isn't that immunogens?
Hello.
An antigen is a non-self marker that is recognised by T-lymphocytes or antibodies produced by B-lymphocytes and triggers a response from a B or T-cell. Antigens that trigger an immune response are referred to as immunogens, but immunogens are still generally referred to using the umbrella term 'antigen'. Essentially, not all antigens will initiate an immune response, but when we usually refer to antigens in this area of study, we refer specifically to immunogens (but this word is less commonly seen) because it's just easier to refer to everything as an 'antigen'.
B and T lymphocytes are specialised white blood cells that respond to pathogens. B-cells initiate the humoral response and T-cells initiate the cell-mediated response, but they both work together in the immune system.
The T-cells we need to know about are these:
Helper T cells - stimulate B cells to divide and form a clone of plasma cells
Cytotoxic T cells - kill virus-infected cells and cancer cells
Suppressor T cells - suppress further action by the immune system once the pathogen is defeated
Memory T cells - 'remember' the pathogen so it can be responded to more efficiently if it enters the body again
Hope this helped!