title: Activation of human T4 cells by cross-linking class I MHC molecules.
abstract: These studies examined whether cross-linking class I MHC molecules results in functional or biochemical responses in human T4 cells. The initial studies demonstrated that cross-linking class I MHC molecules either by culturing highly purified T4 cells with immobilized mAb to class I MHC Ag or reacting the T4 cells with mAb to class I MHC Ag and then cross-linking the mAb with goat antimouse Ig (GaMIg) enhanced T4 cell proliferation induced by an immobilized mAb to CD3, OKT3. More-over, immobilized but not soluble mAb to class I MHC Ag enhanced T4 cell proliferation induced by the combination of two mAb to CD2, OKT11, and D66.2. Finally, T4 cells reacted with mAb to CD3 and class I MHC Ag proliferated in the presence of IL-2 when cross-linked with GaMIg more vigorously than T4 cells reacted with either mAb alone. Cross-linking class I MHC molecules was also found to stimulate T4 cells directly. T4 cells reacted with mAb to class I MHC Ag or beta 2 microglobulin and cross-linked with GaMIg proliferated vigorously in the presence of IL-2 or PMA. In addition, it was demonstrated that cross-linking class I MHC molecules by culturing T4 cells with immobilized mAb to class I MHC Ag induced T4 cell proliferation in the presence of IL-2. T4 cell proliferation in the presence of IL-2 and PMA could also be induced by reacting the cells with specific mAb to polymorphic determinants on class I MHC molecules and cross-linking with GaMIg. Cross-linking mAb to CD4 or CD11a did not have a similar functional effect on T4 cells. Finally it was demonstrated that adding GaMIg to T4 cells reacted with mAb to class I MHC Ag but not CD11a resulted in an increase in intracellular calcium concentration. The data demonstrate that cross-linking class I MHC molecules results in the generation of at least one activation signal, a rise in intracellular calcium concentration, and, thereby, stimulates human T4 cells.
mesh_terms: D000276:Adjuvants, Immunologic / Q000276:immunology; D000328:Adult; D000911:Antibodies, Monoclonal / Q000276:immunology; D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology*; D003432:Cross-Linking Reagents; D000939:Epitopes / Q000276:immunology; D006680:HLA Antigens / Q000276:immunology*; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects; D010641:Phenotype; D013601:T-Lymphocytes / Q000145:classification* / Q000276:immunology / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D000276:Adjuvants, Immunologic; D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D003432:Cross-Linking Reagents; D000939:Epitopes; D006680:HLA Antigens; D007376:Interleukin-2; D013755:Tetradecanoylphorbol Acetate