title: Lethal graft-vs-host disease induced by a class II MHC antigen only disparity is not mediated by cytotoxic T cells.
abstract: Treatment of C57BL/6J (B6) murine splenocytes with L-leucyl-L-leucine methyl ester (Leu-Leu-OMe) selectively removes NK cells, CTL precursors, and the capacity to cause lethal graft-vs-host disease (GVHD) in irradiated B6 X DBA/2 F1 mice. In contrast, alloantigen-induced L3T4(+) Th cell function has been shown to be relatively preserved after exposure to this agent. The present studies assessed the effects of Leu-Leu-OMe treatment of donor cells on induction of lethal GVHD in other murine strain combinations. When irradiated B6 X CBAF1 mice were infused with T and NK cell-depleted B6 bone marrow cells and 3 to 30 X 10(6) B6 spleen cells, uniformly lethal GVHD was observed. However, B6 X CBAF1 recipients of T and NK-depleted B6 bone marrow cells and similar numbers of Leu-Leu-OMe-treated B6 spleen cells demonstrated 90 to 100% long term survival. In contrast, Leu-Leu-OMe treatment of B6 donor cells had no beneficial effect on mortality rates in irradiated (B6 X B6-C-H-2bm12)F1 (B6 X bm12F1) recipients. When B6 spleen cells were stimulated in vivo or in vitro with either B6 X CBAF1 or B6 X bm12F1 stimulator cells, the capacity to generate alloantigen-specific CTL was abolished comparably by Leu-Leu-OMe treatment. Thus, the dramatic difference between the effects of Leu-Leu-OMe treatment of B6 spleen cells on the course of GVHD in B6 x CBAF1 and class II MHC only disparate B6 x bm12F1 recipients could not be explained by unique resistance of bm12-specific CTL precursors to Leu-Leu-OMe. These findings indicate that T cell effector mechanisms distinct from classic cell-mediated cytotoxicity are sufficient to generate lethal GVHD in class II MHC only disparate B6----B6 X bm12F1 mice.
mesh_terms: D000818:Animals; D003433:Crosses, Genetic; D003602:Cytotoxicity, Immunologic / Q000187:drug effects; D004151:Dipeptides / Q000494:pharmacology; D005260:Female; D006086:Graft vs Host Disease / Q000209:etiology* / Q000276:immunology / Q000401:mortality; D000949:Histocompatibility Antigens Class II / Q000235:genetics / Q000276:immunology*; D007166:Immunosuppressive Agents / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D013154:Spleen / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000187:drug effects / Q000276:immunology*; D001613:beta 2-Microglobulin / Q000235:genetics / Q000276:immunology*
chemical_list: D004151:Dipeptides; D000949:Histocompatibility Antigens Class II; D007166:Immunosuppressive Agents; D001613:beta 2-Microglobulin; C045139:leucyl-leucine-methyl ester