AP BIOLOGY

Detailed explanation-1: -Helper T cells are arguably the most important cells in adaptive immunity, as they are required for almost all adaptive immune responses. They not only help activate B cells to secrete antibodies and macrophages to destroy ingested microbes, but they also help activate cytotoxic T cells to kill infected target cells.

Detailed explanation-2: -Helper T cells stimulate the B cell through the binding of CD40L on the T cell to CD40 on the B cell, through interaction of other TNF-TNF-receptor family ligand pairs, and by the directed release of cytokines.

Detailed explanation-3: -B cells interact with follicular CD4 T cells to initiate their activation and proliferation leading to terminal differentiation of immunoglobulin-producing plasma cells (27, 32). B and T cell interaction in turn initiates activation of follicular CD4 T cells and their effector function (27).

Detailed explanation-4: -The helper T-cells release molecules called cytokines. Cytokines send messages to other immune cells to start an immune response.