A MOUSE MONOCLONAL-ANTIBODY SPECIFIC FOR THE V-BETA-5.3 CHAIN OF THE HUMAN TCR RECOGNIZES A SUBGROUP OF THE MOUSE TCR V-BETA-8.2 CHAINS

We have analyzed the reactivity of a mouse monoclonal antibody directe d against the human T cell receptor for antigen (TCR). This antibody ( 111-427) of immunoglobulin G1 isotype has been produced in a BALB/c mo use immunized with HPB-ALL cells and normal human peripheral blood leu kocytes. It reacts specifically with the HPB-ALL lymphoma and 2 to 7% of normal human blood lymphocytes, on which it has a mitogenic effect in vitro, We have shown that it immunoprecipitates the alpha beta TCR of HPB-ALL and that it is specific for the V beta 5.3 chain of the hum an TCR, In addition, we have observed that this antibody stains a mino r fraction of T lymphocytes in different strains of mice. We have scre ened a number of murine T cell clones or hybridomas and have found tha t the T cell hybrid line DO.11.10.S4.4 is positive. We have been unabl e to immunoprecipitate reproducibly the molecule recognized by 111-427 after I-125 cell surface labeling and cell lysis in NP-40 or digitoni n, probably because of low-affinity binding. On Western blotting, 111- 427 revealed one band that has an apparent molecular mass of 89 kDa in nonreducing conditions and disappears after reduction. Similar result s were obtained in parallel with the F23.1 and F23.2 antibodies. Thus, this antibody appears to recognize an epitope present primarily on th e V beta 8.2 chain of the mouse TCR, We have assayed its capacity to s timulate splenic T lymphocytes in vitro, We have observed that it is c apable of triggering, to a minor degree in soluble form and very effec tively when coupled to Sepharose beads, the proliferation of spleen T lymphocytes from mice chronically infected with the blood parasite Try panosoma cruzi.