Activated human T cells can present alloantigens but cannot present soluble antigens.
Human T cells, when activated by antigen or mitogen, express Ia antigens. We have examined the capacity of activated T cells to stimulate autologous and allogeneic T cells and their ability to present soluble antigen. Interleukin 2-dependent T-cell lines (TCL), free of accessory cells, were used for antigen-presenting cells. These activated T cells were potent stimulators in an autologous mixed lymphocyte reaction (AMLR), more so than autologous irradiated non-T mononuclear cells. Activated T cells were also able to stimulate proliferation of allogeneic T cells in the absence of any other accessory cells, and this stimulation was blocked by anti-Ia antibodies. Resting unstimulated T cells were unable to stimulate autologous or allogeneic responses. Thus, activated T cells were able to present self antigens and alloantigens. However, activated T cells could not present soluble antigens to autologous T cells or to antigen-specific TCL even if exogenous interleukin 1 was added to cultures. The ability of activated T cells to stimulate an AMLR in vitro may reflect an important immunologic amplification mechanism in vivo. The ability of activated T cells to present alloantigens but not soluble antigens suggests an inability to process antigen, and this may provide further insights into the complexities of antigen presentation.
D000938:Antigen-Presenting Cells / Q000276:immunology*; D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface / Q000032:analysis; D002460:Cell Line; D002478:Cells, Cultured; D000949:Histocompatibility Antigens Class II / Q000032:analysis; D006801:Humans; D007375:Interleukin-1 / Q000276:immunology; D007519:Isoantigens / Q000276:immunology*; D008213:Lymphocyte Activation; D012995:Solubility; D013601:T-Lymphocytes / Q000276:immunology*
D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D000949:Histocompatibility Antigens Class II; D007375:Interleukin-1; D007519:Isoantigens