The search for H-2 complementation affecting the anti-Thy-1 response in mice: a progress report.

It has been postulated that combinatorial Ia molecules of IAb/Iad heterozygotes are involved in the recognition of the Thy-1 alloantigens. These molecules could be considered the products of the complementary Ir-Thy-1 genes. In present studies, no complementation was found among 37 different H-2 heterozygous F1 hybrids except those carrying IAb/IAd haplotypes. However, in two instances involving hybrids carrying IAr alleles anti-Thy-1 responses were found to be better than expected. The possible mechanism(s) of such responses is currently under investigation.