Final answer:
The bulk of central tolerance is achieved by T cells due to their complex selection process in the thymus and their critical role in aiding B cells' immune responses. B cell tolerance mechanisms are less understood but include negative selection and anergy. T cells also exert control over peripheral B cell tolerance by preventing activation and survival of self-reactive B cells, showcasing the importance of T cell-mediated tolerance in preventing autoimmunity.
Step-by-step explanation:
Central tolerance is crucial in preventing autoimmunity by eliminating self-reactive lymphocytes. T cells undergo a rigorous selection process in the thymus, involving both positive and negative selection. Negative selection eradicates T cells that strongly bind to self-antigens, while positive selection retains those that bind MHC molecules properly.
B cell tolerance also involves negative selection in the bone marrow, through which self-reactive B cells can undergo apoptosis, receptor editing, or become anergic. However, the maturation and tolerance mechanisms in B cells are not as thoroughly understood as those in T cells. An additional layer of immune regulation called peripheral tolerance is also critical, with regulatory T cells maintaining tolerance by inhibiting self-reactive cells that escape the thymus.
Peripheral tolerance in B cells is also influenced by T cells. Most protein antigens require help from T cells for B cells to produce antibodies. If a self-reactive B cell does not receive necessary signals from T cells, it is led to apoptosis. This dependency illustrates the extensive control T cells exert over B cells and the importance of T cell-mediated mechanisms in preventing autoimmunity.