title: Characterization of two distinct primary T cell populations that secrete interleukin 2 upon recognition of class I or class II major histocompatibility antigens.
abstract: This study has characterized the primary T cell subpopulations that secrete IL-2 in response to recognition of either class I or class II MHC encoded determinants. The addition to culture of anti-IL-2-R mAb inhibited the consumption of IL-2 by activated lymphocytes during the response period, permitting a much more accurate assessment of the amount of IL-2 produced in the response cultures. Using this response system, we found that primary T cell populations contain two IL-2-secreting T cell subsets that express reciprocal phenotypes and different MHC recognition specificities: an L3T4+, Lyt-2- T cell subset responsive to both class I and class II MHC alloantigens, and an L3T4-Lyt-2+ T cell subset responsive only to class I MHC alloantigens. The L3T4+ T cell subset expressed a broad functional response repertoire in that L3T4+ T cells were triggered to secrete IL-2 upon recognition of unmodified self-Ia determinants, allogeneic Ia determinants, and class I alloantigens presented by self-Ia determinants. The activation of L3T4+ IL-2-secreting T cells, even those responsive to class I MHC alloantigens, could be blocked completely by anti-Ia mAbs, confirming that the L3T4+ T cell subset was in fact class II restricted. In contrast, the Lvt-2+ T cell subset expressed a narrow functional response repertoire in that they were triggered to secrete IL-2 only in response to allogeneic class I MHC determinants, and were not triggered to secrete IL-2 even in response to TNP-modified self-MHC determinants. The specificity of Lyt-2+ IL-2-secreting T cells for class I MHC allodeterminants was confirmed by the observations that: (a) their activation could be blocked completely by anti-class I mAbs, (b) they could be triggered by Ia- cell lines which expressed class I MHC alloantigens and possessed accessory function, and (c) they responded to class I MHC alloantigens but failed to respond to class II MHC alloantigens, even in the presence of exogenously added second signals that circumvented the requirement for alloantigen-bearing accessory cells. Finally, the frequency of primary Lyt-2+ T cells that secreted IL-2 in response to class I (Kbm1) MHC alloantigens was shown to be only minimally lower than that of L3T4+ T cells that secreted IL-2 in response to class II (I-Abm12) MHC alloantigens.(ABSTRACT TRUNCATED AT 400 WORDS)
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000936:Antigen-Antibody Complex; D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface / Q000032:analysis; D002478:Cells, Cultured; D006183:H-2 Antigens / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D007111:Immunity, Cellular; D007376:Interleukin-2 / Q000096:biosynthesis*; D008213:Lymphocyte Activation; D008285:Major Histocompatibility Complex; D051379:Mice; D011971:Receptors, Immunologic / Q000276:immunology; D015375:Receptors, Interleukin-2; D013601:T-Lymphocytes / Q000145:classification / Q000276:immunology* / Q000378:metabolism; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology* / Q000378:metabolism; D014301:Trinitrobenzenes / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D006183:H-2 Antigens; D000949:Histocompatibility Antigens Class II; D007376:Interleukin-2; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2; D014301:Trinitrobenzenes