Immunity from certain microbes is part of the unique genetic makeup of each species. Protects by innobilize, neurtalize, or destroy design and failure is immediately fatal due to massive uncontrollable infection. Then migrate to lymph nodes and express the antigen which they recognize and generate antibodies against. Increased numbers of the lymphocyte are produced only after the antigen has made its way into the organism. After T cells are activated they go out into the circulation, recognize, and neurtralize antigen bearing cells.
Complete antigens are molecules that have immounogenicity and reactivity.
Usually single antigens stimulate many lynphocytes. B cells generate humoral immune response 1. When antigen finds the B cell which recognizes it specifically it binds to B cell and causes B cell to start dividing. This is primary immune response. This is secondary immune response.