Non-lymphoid thymic components tolerize T cell precursors to all the minor histocompatibility antigens of the thymus-donor strain.
Two months after adult-thymectomy, male B10.D2 mice were irradiated (6.5 Gy), injected with B10.D2 bone marrow cells and grafted with untreated neonate (DBA/2 X B10.D2)F1 (H-2d/H-2d) thymus [D2.F1]. Control (D2.D2) mice were implanted with B10.D2 thymus. T cells from [D2.F1] mice revealed to be fully immunocompetent while being tolerant to the minor histocompatibility antigens (MiHA) differing between DBA/2 and B10.D2 strains by in vitro and in vivo assays. Their transplantation into F1 irradiated (8.5 Gy) recipients did not induce any clinical sign of graft-versus-host reaction (GVHR) whereas this reaction is lethal when the transplantation is realized with normal B10.D2 or [D2.D2] hemopoietic cells. (D2.F1) transplanted cells were not stimulated to divide in non-lymphoid organs of the F1 hosts while this stimulation is a characteristic feature of the early period of the GVHR. Tolerance was due neither to detectable chimerism of the thymus-grafted host nor to active suppression. It is concluded that the thymus plays a sufficient and essential role for the proper acquisition of T cell immunocompetence and tolerance to all the minor histocompatibility antigens of the thymus-donor strain. Since we have previously reported that MiHA are numerous and highly organ-specific, the expression or the presence of all these MiHA in the non-lymphoid components of the thymus is questioned.
D000818:Animals; D006649:Histocompatibility Antigens / Q000276:immunology*; D007108:Immune Tolerance; D008297:Male; D051379:Mice; D013601:T-Lymphocytes / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology; D013934:Thymectomy; D013950:Thymus Gland / Q000637:transplantation
D006649:Histocompatibility Antigens