B lymphocytes are principal cells that mediate humoral adaptive immunity. After their maturation in the bone marrow, B cells enter peripheral lymphoid tissues, which are the sites of interaction with foreign antigens. Production of antibodies is initiated by the interaction of antigens with a small number of mature B cells specific for each antigen. An antigen binds to the membrane receptors on specific B cells and initiates a series of responses that lead to two principal changes: cell proliferation resulting in expansion of the clone, and differentiation to either plasma cells actively secreting antibodies or to memory cells.
Key words: B cells, subsets of B cells, memory B cells, plasma cells