Differential ability of B10, B10.D2, BALB/c, and B6D2F1 recipients to reject allogeneic and β2m^−/− BMC. (A) The engraftment of allogeneic BMCs after transfer of 7.5 or 15 million B10.D2 BMCs into B10 recipients or 7.5, 15, or 25 million B10 BMCs into B10.D2 recipients is shown. (B) The engraftment of 50 or 100 million MHC class I deficient BMCs (β2m^−/−) in H2d strains (BALB/c and B10.D2) is shown. (C) The engraftment of 50 or 100 million MHC class I-deficient BMC (β2m^−/−) after transfer into B6D2F1 (H2^bxd) recipients is shown. In all experiments, some groups were treated with anti-NK1.1 (PK136) or anti-ASGM1 to promote engraftment by removing host NK cells 2 days before BMT. Seven days after transplantation, hematopoietic progenitor content of the spleens (total CFU-c per spleen) was assessed (mean ± SEM) to determine engraftment. N.D. indicates not done. One-way ANOVA was performed to determine whether the mean values were significantly different (P < .05). Each experiment was performed 2 or 3 times.