title: L3T4+ T-cell-independent reactivity of Lyt2+ T cells in vivo.
abstract: The aim of this study was to analyze in vivo the L3T4+ T-cell-subset-independent reactivity of Lyt2+ T cells toward transplantation alloantigens. To this end, we depleted normal mice of L3T4+ T cells by injection of monoclonal antibodies to the L3T4 antigen. This procedure not only led phenotypically to a disappearance of L3T4+ T cells, but also effectively abolished reactivity toward class II MHC antigens in vitro and in vivo. However, L3T4+ T-cell-depleted mice still reacted to class I MHC alloantigens in vivo: after immunization with class I MHC alloantigens Il-2 receptor-bearing T cells appeared in the draining lymph nodes, and developed antigen-specific cytolytic activity. Moreover, upon in vivo priming the frequencies of class I MHC-specific precursors of Il-2-producing and cytolytic Lyt2+ T lymphocytes increased up to 20-fold. L3T4+ T-cell-depleted mice rejected class I MHC-bearing skin grafts promptly. We conclude that not only in vitro but also in vivo Lyt2+ T cells remain reactive toward class I MHC antigens in the absence of L3T4+ T helper cells.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology; D000950:Antigens, Ly / Q000032:analysis; D003602:Cytotoxicity, Immunologic; D006084:Graft Rejection; D006183:H-2 Antigens / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D007111:Immunity, Cellular; D007376:Interleukin-2 / Q000096:biosynthesis; D008211:Lymphocyte Cooperation; D051379:Mice; D012867:Skin / Q000276:immunology; D016038:Skin Transplantation; D013601:T-Lymphocytes / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D000950:Antigens, Ly; D006183:H-2 Antigens; D000949:Histocompatibility Antigens Class II; D007376:Interleukin-2