BM allografts induce deletion of donor-specific T cells. Sublethally irradiated B6 mice were grafted with DBA/2 BM coinjected (or not) with 2.106 Thy1.1+ Treg in vitro cultured in presence of DBA/2 antigen-presenting cells. Control syngeneic chimeras were realized by reconstituting sublethally irradiated B6 and DBA/2 mice with syngeneic BM. TCR-Vβ3, Vβ5, Vβ6-expressing CD4+ T cells are specific for superantigens presented in DBA/2 (but not B6) mice. The percentage of Vβ+ cells among host CD4+ T cells was assessed by flow cytometry in the spleen (A) and thymus (B) at the indicated time points after reconstitution. Vβ4-expressing T cells do not recognize superantigens in DBA/2 mice. Indicated are mean values ± SD (n ≥ 4, 4 independent experiments). *P < .05, **P < .01, ***P < .001. ns, not significant, Student t test.
