Describe the steps involved in activating an antibody response to an antigen.

When an antigen enters the body, the immune system launches an attack against it by the production of antibodies. They are produced by the white blood cells called the B lymphocytes or the B cells. The antigen binds to the B-cell surface and stimulates the B cell to undergo clonal selection producing a group of identical cells called a clone. They divide by mitosis and produce the plasma cells and the memory cells. The plasma cells produce antibodies which destroy the antigen. This is the primary immune response and a mechanism of humoral immunity. The memory cells keep circulating in the body and respond by producing antibodies on encountering the same antigen again, generating the secondary immune response.