The role of H-2 regions in overcoming tissue incompatibility.

Neonatal transplantation tolerance to the products of the H-2 beta complex was induced in B10.A (H-2 alpha) mice. On the basis of the survival of skin allografts it was found that antigens determined by the D region of the H-2 alpha complex (of the B10.A(2R) strain) were most easily overcome and that tolerance to the products of the D end of the H-2 complex (of the B10.A(4R) strain) was also easy to induce. The antigens produced by the K end of H-2 (of the B10.A(5R) and B10.A(3R) strains) represented a stronger incompatibility barrier and a difference in the entire H-2 beta complex caused strongest resistance to tolerance induction. When tolerance to the products of the entire H-2 beta complex was induced in newborn B10.A mice, and the neonatally treated animals were grafted simultaneously with five different grafts, those disparate at the K end of H-2 and in the entire H-2 region were rejected in some animals, while the grafts disparate at the D end of H-2 remained intact in the same mice. No dependence on the I-J subregion was observed in this system. Furthermore, tolerance was more easily inducible in male than in female B10.A mice.