Final answer:
The statement is false because T cells, upon activation, assist in the maturation of B cells into plasma cells, which are the immune cells responsible for secretion of antibodies, not the T cells themselves.
Step-by-step explanation:
The statement that upon activation of T cells via the 2 signals, it secretes IL-2,4,5, which leads to plasma cells secreting is False. Activated T cells indeed secrete cytokines such as interleukins, but it is the B cells, not T cells, that differentiate into plasma cells which are responsible for the secretion of antibodies. Specifically, T cells secrete various cytokines that help the B cell to proliferate and mature into an antibody-producing plasma cell. Activation of B cells is a crucial step in clonal selection which leads to the production of plasma cells that secrete antibodies specific to an antigen.
Cytokines secreted by the T cells provide help to B cells to multiply and differentiate into plasma cells. However, plasma cells arise from B cells, not directly from T cells. Therefore, the correct understanding is that T-cell activation leads to the secretion of cytokines which then assists in the B cell's maturation into plasma cells.