Antigen selects those lymphocytes that possess the specific receptor
Each B‐cell is programmed to make one, and only one, specificity of antibody and it places a transmembrane version of these antibodies on its cell surface to act as receptors for the specific antigen. These antibodies can be detected by using fluorescent probes and, in Figure 2.8c, one can see the molecules of antibody on the surface of a human B‐lymphocyte stained with a fluorescent rabbit antiserum raised against a preparation of human antibodies. Each B‐lymphocyte has of the order of 105 antibody molecules, all of identical antigen specificity, on its surface. The B‐cells give rise to plasma cells (Figure 2.8 d,e), which produce large amounts of soluble antibody in their rough endoplasmic reticulum (Figure 2.8 f ). The antibody is then secreted from the plasma cells into the local environment and can circulate, become attached to cells bearing Fc receptors, or be transported to mucosal surfaces.