T cell recognition of nonpolymorphic determinants on H-2 class I molecules.
Recognition of polymorphic determinants on class I or class II MHC Ag is required for T lymphocyte responses. Using cell-size artificial membranes (pseudocytes) bearing H-2 class I Ag it is demonstrated that T cells can, in addition, recognize nonpolymorphic determinants on class I proteins. Pseudocytes bearing class I alloantigen stimulate in vitro generation of secondary allogeneic CTL responses. At a suboptimal alloantigen surface density, incorporation of class I molecules identical to those of the responder cells (self-H-2) or from third-party cells resulted in dramatically enhanced responses, whereas incorporation of class II proteins had no effect. The receptor that mediates recognition of conserved class I determinants has not been identified, but results of antibody blocking studies are consistent with the Lyt-2/3 complex of CTL having this role. Thus, class I proteins on Ag-bearing cells can have two distinct roles in T cell activation, one involving recognition of polymorphic determinants by the Ag-specific receptor and the other involving recognition of conserved determinants.
D000818:Animals; D000954:Antigens, Surface / Q000276:immunology; D002460:Cell Line; D003602:Cytotoxicity, Immunologic; D000939:Epitopes / Q000235:genetics / Q000276:immunology*; D006183:H-2 Antigens / Q000235:genetics / Q000276:immunology*; D008567:Membranes, Artificial; D051379:Mice; D008806:Mice, Inbred AKR; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D011110:Polymorphism, Genetic; D013234:Stem Cells / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*
D000954:Antigens, Surface; D000939:Epitopes; D006183:H-2 Antigens; D008567:Membranes, Artificial