GENERATION OF CD4-POSITIVE SUPPRESSOR T CELLS FROM MIXED LYMPHOCYTE CULTURES IN THE PRESENCE OF INTERLEUKIN 2 RECEPTOR ANTIBODY TÜ69

Abstract

The specificity of a novel monoclonal antibody (moAB), TÜ69, directed to the interleukin 2 receptor (IL-2R) was verified by sequential immunoprecipitation with anti-Tac. TÜ69 cross-competed with anti-Tac in binding analyses. When TÜ69 was added during the sensitization of normal peripheral blood mononuclear cells (PBMC) to allogeneic HLA-class I or-class II mismatched stimulator PBMC, alloproliferative responses and specific cytotoxicity were no longer detectable and the generation of natural killer (NK)-like effector cells was partially inhibited. Remarkably, however, the generation of CD4+ nonspecific suppressor T cells in such mixed lymphocyte cultures (MLC) was not inhibited—but, in contrast, was strongly enhanced in the presence of TÜ69. These suppressor cells inhibited unrelated allospecific responses in vitro to background levels even at a ratio of 50:1 responder:irradiated suppressor T cell lines. Such a potent experimental suppressor system