Update on therapeutic monoclonal antibodies.

Monoclonal antibodies are among the most important class of drugs introduced into the therapeutic armamentarium since the introduction of antimicrobials in the 1930s. The first therapeutic monoclonal antibody, the anti T-cell monoclonal antibody OKT4, was licensed in 1986. Since then, 18 additional antibodies have been licensed in the US, with many more in the pipeline. Before 1986, many monoclonal antibodies were available for laboratory studies, notably to identify specific cells in the blood and tissues. This is best illustrated by the cluster designation (CD) system for antigens present on hematopoietic cells, now numbering over 200.