Adjuvants cannot stimulate an immune response by themselves. Once a B cell encounters an antigen, the B cell produces identical antibodies that recognize and bind to only the antigen that stimulated the B cell. Each antibody has a slightly different amino acid sequence that renders it specific to only one antigen.
Antigens can be proteins, carbohydrates, nucleic acids, hormones, or other substances.
Lupus, rheumatoid arthritis, and multiple sclerosis are examples of human autoimmune disease. B cells may be found in the bone marrow and in the blood circulation. Some CD antigens have a well-known function, but other CD antigens have no known function. Cytokines can be both immunostimulatory and immunosuppressive. Interleukins, interferons, and some growth factors are examples of cytokines.