B cells are lymphocytes that play a large role in the humoral immune response (as opposed to the cell-mediated immune response, which is governed by T cells). The principal functions of B cells are to make antibodies against antigens, perform the role of Antigen Presenting Cells (APCs) and eventually develop into memory B cells after activation by antigen interaction. B cells are an essential component of the adaptive immune system.
Development of Immunity Mode of Action
When antigen enters the body it stimulates B-lymphocytes in blood to produce antibodies specific to antigen which attack and destroy it, after the initial attack number of specific antibodies in the blood falls slowly over several weeks, but the body remembers the structure and can produce in short notice subsequent invasion of same antigen is therefore rapidly halted and specific immunity is acquired, when second antigen is encounter the lymphocytes must produce new antibody since the first antibody is specific only to first antigen ,second antibody continuously circulate on the blood stream and immunity to second antigen is acquired.