Proteins made by the B cells of the immune system, which recognize and neutralize foreign invaders such as bacteria and viruses. An antibody identifies a specific part of the target, known as an antigen, and binds to it so as to neutralize it.
In a relatively recent form of treatment, monoclonal antibodies (highly specific antibodies made in the laboratory) are used to bind specifically to target cells or proteins. Monoclonal antibody therapy can be used to destroy malignant tumor cells and block their growth. The monoclonal antibodies infliximab (brand name Remicade), adalimumab (Humira), golimumab (Simponi), and certolizumab (Cimzia) are used to treat autoimmune diseases such as Crohn disease, ulcerative colitis, and rheumatoid arthritis by inhibiting the action of tumor necrosis factor (TNF), a cytokine (chemical messenger) that promotes inflammation. Tociluzimab (Actemra) inhibits another pro-inflammatory cytokine called interleukin-6 (or IL-6). Rituximab (Rituxan) is a monoclonal antibody that temporariy decreases the number of B cells, the white blood cells that manufacture antibodies.