Differentiation antigens on rhesus monkey lymphocytes II. Characterization of RhT3, a CD3‐like antigen on T cells

A monoclonal antibody FN18 is described, which is specific for mature rhesus monkey T lymphocytes. It defines a cell surface antigen, composed of two polypeptide chains with a molecular mass of 22 and 27 kDa. In view of these and other similarities with the human T3 or CD3 antigen, it was designated as RhT3. Expression, distribution and certain functions of RhT3 were compared with those of its human counterpart. Analogous to anti-CD3 antibodies in man, FN18 is able to modulate its target antigen, has mitogenic properties and is able to block the pokeweed mitogen and concanavalin A-driven cell proliferation, but not that caused by phytohemagglutinin. In spite of such minor dissimilarities the available data strongly suggest that the RhT3 antigen is the rhesus monkey's homologue of the human CD3 antigen.