Differentiation antigens on rhesus monkey lymphocytes. I. Identification of T cells bearing CD3 and CD8, and of a subset of CD8-bearing cells.

Rhesus monkeys provide an excellent preclinical model to test the effect of monoclonal antibodies (mAb) in vitro and in vivo. So far, mostly mAb have been used which were originally raised against human cell surface antigens but cross-reacted reasonably well with homologous antigens on rhesus monkey cells. However, to optimize the model, it was necessary to produce mAb which react specifically with subsets of rhesus monkey lymphocytes. In this report, three mouse anti-rhesus monkey mAb are described, specific for different subsets of rhesus monkey T lymphocytes. None of the reagents cross-reacts with human lymphocytes. Characterization of these mAb was based upon indirect immunofluorescence, using a simultaneous staining technique, and immunoprecipitation of the specific target antigens. One antibody (GM9) reacts with the same subset as is recognized by mAb specific for human CD8+ cells. The second mAb (GM13) is specific for a subset of CD8+ cells. A third mAb (FN18) was of particular interest: it identifies a cell surface complex, RhT3, expressed on mature T lymphocytes, of which the polypeptide chains have a molecular mass of 22 and 27 kDa. The data strongly suggest that RhT3 is a CD3-like determinant, so far unidentified in the rhesus monkey.