Conditions for the generation of autoreactive human T cell clones: requirement for lymphokines other than interleukin 2 alone

In an attempt to determine whether factors other than interleukin (IL) 2 alone were necessary for the generation of autoreactive suppressive T cell clones, lymphocytes from HLA-Dw-matched allogeneic mixed leukocyte cultures (MLC) were propagated and cloned in purified IL 2, partially purified IL 2, conditioned medium (CM) from stimulated peripheral blood mononuclear cells (PBMC), or with purified IL 2 plus IL 3, IL 4, or interferon-gamma (IFN-gamma). Cloning efficiencies were very low in all cases (less than 10%) and of 48 clones tested only 6 were capable of autocrine proliferation after stimulation with autologous PBMC. Four of these clones were derived from populations expanded and cloned in CM, one from cultures with partially purified IL 2, and one with purified IL 2. All were CD4+ alpha/beta-T cell receptor. Their stimulation was blocked by anti-DR and broadly reactive MHC class II-specific monoclonal antibodies (mAb) but not by anti-DQ or anti-DP mAb. One clone was blocked exclusively by broad mAb but not by anti-DR, -DQ, or -DP mAb, and this was the only clone to suppress lymphocyte proliferation in allogeneic MLC, a property previously described for autoreactive clones derived under similar conditions detecting potentially novel lymphocyte activating determinants designated "DY." These results therefore suggest that DY-specific autoreactive suppressive clones are produced under these conditions only at a low frequency and that an unidentified factor other than IL 2, IL 3, IL 4, or IFN-gamma is involved in their generation.