When an antigen binds to it, the B cell gets activated. It switches from displaying the receptor on its surface to secreting it, in the form of an antibody, into the blood. Even further mutations accumulate in the B cell, refining the antibody’s binding to the antigen.II Ultimately, the B cell matures into a cell so single-mindedly dedicated to antibody production that its structure and metabolism are altered to facilitate the process. It is now a cell dedicated to making antibodies—a plasma cell. Some of these plasma cells also become long lived and retain the memory of the infection.
