Evidence for Immunization of F1 Hybrid Mice Against Parental Transplantation Antigens

Abstract

Previous grafting of parental spleen cells or skin accentuated secondary morbidity and mortality in F1 hybrid mice subsequently exposed to 900 r of X rays and inoculated with 107 marrow cells from donors of the same parental strain. The intensity of this effect varied in relation to the extent of H-2 histocompatibility differences among the parental strains. It was maximal when (C3H Anf X 101)F1 and (C57BLX101)Fi mice were "immunized" and grafted with C3H Anf and C57BL cells, respectively; minimal when (BALB/c X A/He)F1 mice were treated with A/He cells and absent when the latter hybrid was treated with BALB/c cells. In no combination did pretreatment of the F1 hybrids with cells homologous to the marrow donor strain affect the morbidity and mortality of the recipient mice. The observed effect is ascribed to "immunization" of the F1 hybrid against parental tissue antigens. It is, therefore, inferred that parental histocompatibility alleles may not necessarily be expressed as co-dominants in F1 hybrid mice.