Final answer:
Th2 cells are best known for producing Interleukin-4 (IL-4), which is crucial for initiating B cell differentiation into antibody-producing cells, unlike Th1 cells, macrophages, and cytotoxic T cells which have other primary immune functions. Option E.
Step-by-step explanation:
The Th2 cells are known as the best producers of Interleukin-4 (IL-4), which is a cytokine that plays a crucial role in the immune system by inducing differentiation of B cells into antibody-secreting plasma cells.
Th1 cells, on the other hand, secrete cytokines that enhance the activity of macrophages and other cells to combat intracellular pathogens.
While macrophages and CD3+CD8+ cells (cytotoxic T cells) also play significant roles in the immune response, they are not primarily responsible for the production of IL-4, as the macrophages primarily act in phagocytosis and promoting inflammation, and cytotoxic T cells target infected cells directly.
B cells can produce IL-4 but are more involved in the antibody production upon activation by Th2 cells. Option E.