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 directed against the human T cell receptor for antigen (TCR). This antibody (111-427) of immunoglobulin G1 isotype has been produced in a BALB/c mouse immunized with HPB-ALL cells and normal human peripheral blood leukocytes. 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 human TCR. In addition, we have observed that this antibody stains a minor fraction of T lymphocytes in different strains of mice. We have screened a number of murine T cell clones or hybridomas and have found that the T cell hybrid line DO.11.10.S4.4 is positive. We have been unable to immunoprecipitate reproducibly the molecule recognized by 111-427 after 125I cell surface labeling and cell lysis in NP-40 or digitonin, 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 results were obtained in parallel with the F23.1 and F23.2 antibodies. Thus, this antibody appears to recognize an epitope present primarily on the V beta 8.2 chain of the mouse TCR. We have assayed its capacity to stimulate splenic T lymphocytes in vitro. We have observed that it is capable of triggering, to a minor degree in soluble form and very effectively when coupled to Sepharose beads, the proliferation of spleen T lymphocytes from mice chronically infected with the blood parasite Trypanosoma cruzi.