title: Antigen presentation to human T lymphocytes. I. Different requirements for stimulation by hapten-modified cells vs. cell sonicates.
abstract: We have investigated the cellular and antigenic requirements for incubation of secondary proliferative responses by human T lymphocytes. Two distinct properties of antigen-presenting peripheral blood mononuclear cells were studied: (a) the ability for appropriate cell surface constituents to construct an immunogenic moiety, and (b) the ability to present similar antigenic determinants when they are not covalently bound. Only Ia+ hapten-modified cells were effective stimulators. In contrast, both Ia+ and Ia- cell sonicates could stimulate secondary proliferative responses, but only in the presence of an accessory cell. This accessory cell was present in Ia+ macrophage, but not in Ia+ non-T lymphocyte, preparations. In contrast, macrophages or soluble factors produced by macrophages were not required for primed T cells to undergo hapten-specific proliferation in response to hapten-modified Ia+ stimulator cells. Thus, although all Ia+ cells tested can stimulate primed cells to proliferate, not all Ia+ cells can function as accessory cells for responses to sonicates. This may reflect the unique ability of a subpopulation(s) of Ia+ cells to bind or process sonicates or soluble antigens for appropriate recognition by primed T cells.
mesh_terms: D000954:Antigens, Surface; D002462:Cell Membrane / Q000276:immunology; D006241:Haptens; D000949:Histocompatibility Antigens Class II; D006801:Humans; D007700:Kinetics; D008214:Lymphocytes / Q000145:classification; D008264:Macrophages / Q000276:immunology; D013010:Sonication; D013601:T-Lymphocytes / Q000276:immunology*; D014465:Ultrasonics
chemical_list: D000954:Antigens, Surface; D006241:Haptens; D000949:Histocompatibility Antigens Class II