Humoral Immunity

Humoral immunity produces antibodies.There are millions of different B lymphocytes each with a different type of immunoglobulin IgM on its surface, each of these antibodies specific for only one antigen.When a B cell encounters the free antigens or the antigen on the pathogen, the antibody will bind to the antigen, the B cell will engulf the pathogen or antigen and will become an antigen-presenting cell.Activated T helper cells bind to the B cell APC. This is called clonal selection. The T helper cells produce interleukins which activate the B cell.The activated B cell divides by mitosis and differentiates into B plasma and B memory cells. This is called clonal expansion.The B plasma cells produce antibodies which are secreted into the blood plasma.The B memory cells will divide rapidly to form B plasma cells if the body is infected again. This is called the secondary immune response.