ABSTRACT
B and T lymphocytes comprise the cellular components of the antigen-specific immune system. The major role of B lymphocytes is the synthesis and secretion of immunoglobulin (Ig) proteins in response to the activation of individual cells by specific antigen. The roles of T lymphocytes are more complex. T cells elicit soluble factors following their activation by antigens in the context of major histocompatibility complex (MHC) molecules on antigen-presenting cells (including B cells). These factors augment immune responses by increasing the proliferation and survival of other cells, including B cells. Functions of T cells also include the direct killing of target cells that present stimulating antigens.
