Drug-induced tolerance to allografts in mice. VI. Tolerance induction in H-2-haplotype-identical strain combinations in mice.

When C3H/HeN (C3H) mice were primed with viable AKR/J (AKR) spleen cells and treated with cyclophosphamide (CP) two days later, a profound tolerance to AKR skin grafts was induced. This tolerance was induced also in other combinations disparate only at minor histocompatibility (H) antigens (AKR-C3H and BALB/c[BALB]-DBA/2[DBA]). In C3H mice made tolerant to AKR, delayed foot-pad reaction (DFR), cytotoxic lymphocytes (CTL), and cytotoxic antibodies (CTAb) against AKR spleen cells were abrogated completely. Tolerance to AKR mice was also observed in C3H mice primed with viable AKR and C57BL/6 (B6) spleen cells and treated with CP, but tolerance to B6 was not induced because a cell population responsible for DFR and CTL against B6 H-2 antigens remained after tolerance induction. These results suggest that there is a lymphocyte population responsible for DFR and CTL against antigens allogeneic at both major and minor H that is less proliferative than the population responsible for DFR and CTL against minor H antigens.