IL-2 is produced by:

Answer is A (T cells) : IL-2 is produced by T helper cells (CD4 cells). Its actions include: Promotes growth and differentiation of T and B cells: interestingly, receptors for IL-2 are present on T cells themselves, and so the secreted IL-2 acts on these very receptors and promotes growth & differentiation of T cells. Promotes cytotoxicity of T cells and NK cells. Promotes secretion of other lymphokines. Note: IL-3 is produced by T cells for hematopoiesis.