2.1.1 B-cells (immunoglobulins)
  • B lymphocyte (B-cell):   A lymphocyte that matures in the bone marrow and then migrates to lymphoid tissues, where a foreign antigen stimulates it to produce antibodies.
  • The precursors of antibody- forming plasma cells; these cells carry immunoglobulin and class II MHC (major histocompatibility complex) antigens on their surfaces.
  • All B cells are antigen specific and respond to only one foreign protein. The spleen and lymph nodes contain many B cells that, because of the large amount of blood passing through these organs, become exposed to new antigens. After a B cell comes in contact with an antigen, it differentiates into either a plasma cell or a memory cell, and then proliferates. Plasma cells produce antigen- specific antibodies. Memory cells are available to produce antibodies quickly if the same antigen reappears. The antigen- antibody reaction is part of the humoral immune response. It is the basis for vaccination and plays a major role in defense against infection from common organisms.
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