Tumor allograft rejection is mainly mediated by CD8+ cytotoxic T lymphocytes stimulated with class I alloantigens in cooperation with CD4+ helper T cells recognizing class II alloantigens.
Presence of the three major pathways (self-Ia restricted, allo-K/D restricted, and allo-Ia restricted pathways) in generating class I-restricted CTL has been reported. The present study was conducted in order to clarify which of the three is the main pathway in mediating tumor allograft rejection. One million EL-4 tumor cells derived from C57BL/6 (B6;H-2b) were inoculated into the various strains of mice that were genetically different from B6. Class I (K/D) Ag-disparate but IA Ag-matched B6.C-H-2bm1 (bm1;Kbm1, IAb, IE-, Db) mice or B10.A (5R) (5R; b, b, k, d) mice could not reject 1 x 10(6) EL-4 tumor cells in spite of the strong generation of CTL against the B6 Ag, suggesting the inability of the self-Ia restricted pathway and the allo-K/D restricted pathway in rejecting tumor allografts. The strains of mice being capable of rejecting EL-4 tumor were disparate from B6 mice in both class I and class II (IA) Ag, suggesting the importance of the allo-Ia restricted pathway in rejecting tumor allografts. To generate CTL against Kb Ag via the allo-Ia restricted pathway in the bm1 mice, 2 x 10(7) B6.H-2bm12 (bm12; b, bm12, -, b) spleen cells were injected into the bm1 mice as a supplementary source of allogeneic APC that possibly raise CTL through CD4+ Th cells of bm1 origin. These bm1 mice became capable of rejecting 1 x 10(6) EL-4 tumor cells. The same was observed in the combination of bm12----B10.A (5R) (b, b, k, d) mice. To further elucidate the role of the class II restricted CD4+ Th cells, anti-CD4 antibody was repeatedly i.v. administered into the C3H/He (C3H; H-2k) or the DBA/2 (DBA; H-2d) mice on days 0, 1, and 4. Injection of anti-CD4 antibody led 1 x 10(6) EL-4 tumor cells to grow and kill the C3H and DBA mice. These results suggest that the main effector CTL pathway involved in tumor allograft rejection is allo-Ia restricted pathway where CD8+ precursor CTL were stimulated by the class II-restricted CD4+ Th cells.
Tomita
Y
Y
Department of Immunology, Kyushu University, Fukuoka, Japan.
Mayumi
H
H
Eto
M
M
Nomoto
K
K
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D016827:CD8 Antigens; D004306:Dose-Response Relationship, Immunologic; D005434:Flow Cytometry; D006084:Graft Rejection; D015395:Histocompatibility Antigens Class I / Q000276:immunology; D000949:Histocompatibility Antigens Class II / Q000276:immunology; D007116:Immunization, Passive; D008213:Lymphocyte Activation; D008211:Lymphocyte Cooperation; D008223:Lymphoma / Q000276:immunology*; D051379:Mice; D008815:Mice, Inbred Strains; D009368:Neoplasm Transplantation; D009374:Neoplasms, Experimental; D016038:Skin Transplantation / Q000276:immunology; D013154:Spleen / Q000166:cytology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*
D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D016827:CD8 Antigens; D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II