So in cell-mediated immunity, after the cytotoxic t-cell is activated by a Th cell, the Tc celll undergoes clonal expansion to produce more cytotoix t cells (effector T cells) and also some T-memory cells as well?
Yep! Prior to activation, cytotoxic T-cells are considered 'naive' (like unactivated B-cells).
The Cell Mediated Response.
1. Pathogen/Antigen is detected as non-self and harmful.
2. Phagocytes (Macrophages) migrate to the site of infection and engulf the pathogen, breaking it down.
3. It presents an antigen fragement on its MHC Class II markers.
4. T Helper cells recognise this antigen, and stimulate the T cells to undergo clonal expansion and divide into Cytotoxic T Cells.
5. They move to the pathogen and release toxic granules to destroy it. Memory T cells are formed in the process for future occurences, and suppresor T cells supress the immune response.
Helper-T lymphocytes need to become activated (by the means that you suggested) and then they can stimulate cytotoxic T-cells...that is, if they are bound to their complementary antigen! Interleukin-2 is the stimulatory cytokine.
'General' T-cells do not undergo clonal expansion to form cytotoxic and memory T-cells; rather it is the naive cytotoxic t-cells (CD8+) which proliferate and differentiate. This is unlike clonal expansion in B-cells, as naive B-cells act as a precursor to their plasma and memory counterparts. I've attached a screenshot from my textbook which establishes this point nicely!
So the cells which T-helper cells stimulate to undergo colonal expansion are T-Cells, which then go onto produce Cytotoxic T-cells and memory cells? So it is not cytotoxic cells which get stimulated directly by T-helper cells?
thanks
Cytotoxic T-cells are stimulated directly by helper-T Cells. It might be beneficial to know that Cytotoxic-T cells are also called 'CD8+' cells, or something. I dunno, I watch a lot of youtube videos for bio and it always seems to come up
Also, according to NOB, suppressor T-cells are another kind of T-cell, therefore they are not created during the clonal expansion of Tc cells. So, all up there are 3 kinds of T-cells: helper, suppressor and cytotoxic!