Genetics of histocompatibility in mice. II. Survey for interactions between minor (non-H-2) antigens by skin grafting.

Twenty-five congenic mouse strains differing at distinguishable minor (non-H-2) histocompatibility loci were paired in 71 different combinations. F1 offspring were used as skin-graft donors for more than 4000 recipients to test whether immune responses to parental strain antigens were statistically independent. Thirty-four (48 percent) of the 71 combinations were predicted adequately by an independent response hypothesis. A simple additive model was consistent with 39 (55 percent) of the observed responses, although 18 of these were among those in agreement with the independent hypothesis. A synergistic response faster than that predicted by either the independent or additive response model was seen in 12 (17 percent) of the combinations. The remaining 5 percent were not well described by any of these models. No strain was represented with unusual frequency among those involved in synergistic interactions.