T-Cells and B-Cells (1 Viewer)

[tempco]

Ok, just to make sure (got my trials tomorrow )

are T-cells activated by free antigens? I've read several sources that say they do, and some that say they dont. I know for sure that B cells are activated by free antigens.. but im not too sure about T cells.. so, if you have any idea, i'd appreciate it!

 

[jims]

i got trials 2morrow to....

im not sure what you mean by free antigens but ill say 'no'. i can only think of 2 things t cells do an neither of them involve acting against the antigen itself.

 

[Halo]

There are many types of T cells. You should specify.

Anyway, helper T cells is indeed 'activated' by (free?) antigens. Other types of T cells, such as killer and memory, I would think not, instead by activated helpers.

I always thought the B cells are activated by activated helper T cells as well - but I am not sure.

My understanding is that the third line of pathogen defense begins with helper T cells recognising an antigen (either by a 'macrophaged' antigen - or a free one?). The helper T cells then multiply and differentiate into other types of T cells, and activates the B cells too.

I too found several sources supporting different notions of the process. So, ask your teacher!

 

[jims]

from the jackaranda n surfing books, they say that a Th cell recognises an antigen off the phagocyte n then stimulates the B cells (either by direct contact or secreting chemicals like interleukins) to undergo clonal proliforation to produce masses of antibodies to act against the antigen.

i took 'free antigen' to mean something like pollen or a toxin. i dont think either t cells act against them.

 

[tempco]

ok cool.. thanks ppl, although i didnt make myself too clear

 

[mitochondria]

Originally posted by jims
... i dont think either t cells act against them...

Just a note on this even if your nek's trial is over... T cells do in fact "act against" (if I haven't misunderstood your meaning there) the antigen/pathogen. If you think carefully, T cells are responsible for the cell-mediated response, they do confront with the antigen/pathogen to a certain extend. For example, Cytotoxic T cells interact directly with the antigen/pathogen do secret lysosome to interfer/destroy the foreign invader.

 

[Halo]

T cells certainly do act against 'free antigens' (I take it as antigens 'floating around' in the system), but we are discussing whether free antigens will provoke the immune response.

jims is probably right. You will need antigen-presenting cells to activate T and B cells. That is, to activate T helper cells you will need a phagocyte (eg. macrophage) that has captured an antigen, before the helper T cells present them to other cells to begin the cell/antibody-mediated response. (Note however there is another mechanism for presenting antigens).