Final answer:
The type of T cell that directs and regulates B cell activity and differentiation is the T helper cell (Th). Th cells secrete cytokines that help stimulate and activate B cells, leading to antibody production and immune response against pathogens.
Step-by-step explanation:
The type of T cell that directs and regulates B cell activity and differentiation is the T helper cell (Th). These cells secrete cytokines that help stimulate and activate B cells, leading to antibody production and immune response against pathogens.
Th cells are crucial for the immune response to most protein antigens, as they provide the necessary help and signals to B cells to produce antibodies. They play a vital role in the adaptive immune system and the formation of immunological memory.