TH cells play a central role in the immune response. These cells are specially prolific cytokine producers. Once activated by an antigen, they can use these chemical messengers to induce the formation of TC cells, activate macrophages and formation of many antibodies by B-cells.
Functions of TH cell are as follows in the next page (Fig. 10.4):
1. An APC encounters and processes an antigen, forming MHC-antigen complexes on its surface.
2. A TH cell receptor binds to the complex, stimulating APC to secrete IL-1.
3. IL-1 stimulates TH cell to produce IL-2, which then stimulates that TH cell to form a clone of TH cells.
4. The cells of this clone in turn produce cytokines, stimulating cell of both immune systems.
