Kinetics of T cells bearing V(β6) capable of recognizing Mls-1a were examined in the thymus and peripheral lymphoid organs of two allogeneic bone marrow chimeras; AKR/J(H-2(k),Thy1.1,Mls-1a)→C3H/He(H-2(k),Thy1.2,Mls-1b) and AKR-J→C57BL/6(H-2b,Thy1.2,Mls-1b). Sequential appearance of host- and donor-derived T cells occurred in the thymus and the peripheral lymphoid organs of both AKR→C3H and AKR→B6 chimeras. The first cells to repopulate the thymus were Thy1.2+ host-derived radioresistant cells, which were synchronized in their development. The host-derived cells in thymus of AKR→B6 chimeras differentiate more rapidly than those in AKR→C3H chimeras. An almost complete replacement from host-derived cells to donor-derived cells occurred by day 21 after reconstitution in AKR→C3H and AKR→B6 chimeras. In the donor-derived thymocytes, none of CD4- or CD8-single positive thymocytes expressed high density of V(β6) in either AKR→C3H or AKR→B6 chimeras, whereas the host-derived thymocytes in AKR→B6 chimeras contained an appreciable number of CD4-single positive thymocytes bearing V(β6). In the peripheral lymphoid organs, T cells bearing V(β6) were virtually abolished in Thyl.1+ cell pool of both AKR→C3H and AKR→B6 chimeras, while V(β6)+ T cells of host-origin were detected in the peripheral lymphoid organs in AKR→B6 chimeras. These results indicated that the donor-derived mature T cells showed deletion of V(β6) in the thymus and the peripheral lymphoid organs in both AKR→C3H and AKR→B6 chimeras, whereas lack of V(β6) deletion was observed in the host-derived mature T cells in the AKR→B6 chimeras. These results suggested that the host-derived thymocytes may likely escape undergoing a negative selection against donor-phenotype in the radiation bone marrow chimeras.
|Number of pages||12|
|Publication status||Published - 1991|
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