Studies on allogeneic inhibition I. Differential behavior of mouse tumors transplanted to homozygous and F1 hybrid hosts

Lymphomas, carcinomas and sarcomas originating in homozygous hosts grew better when transplanted into syngeneic mice than in F1 hybrids between the syngeneic and an allogeneic strain. The growth inhibition in F1 hybrids was called allogeneic inhibition. In order to demonstrate the phenomenon small inocula had to be used, as a rule below 106 cells. It was demonstrated with tumors originating in seven different mouse strains tested (A, A.SW, A.CA, A.BY, C57BL, C57L and C3H). Allogeneic inhibition was also detected with isoantigenic variant sublines, selected from an (A × A.SW)F1 hybrid lymphoma for compatibility with the A or A.SW parental strains, the variants giving more tumors in the selective A or A.SW strains than in (A × A.SW)F1. The unselected (A × A.SW)F1 lymphoma from which the variants were derived grew as well in (A × A.SW)F1 as did the variants in their selective parental strains.