Back-crossing F1 (BN X PVG) rats with the PVG strain gives hybrids with high natural killer (NK) cell activity.

The genetic regulation of rat natural killer (NK) cell activity against the lymphoma YAC-1 in two rat strains, BN and PVG, with low and intermediate NK activity respectively, was studied. The F1 (BN X PVG) and the BN X F1 (BN X PVG) hybrids were both found to have NK activity intermediate between the BN and PVG parental strains, whereas approximately half of the PVG X F1 (BN X PVG) had high NK activity. No correlation to AgB types was found. Apparently at least two genes regulate NK activity in the rat, neither of which appears to be linked to the major histocompatibility complex.