Genetic control of resistance to tumors.

Hybrid resistance to a BALB/c plasmacytoma, MPC-11, has been investigated. The results indicate that heterozygosity within the H-2 complex is neither necessary nor sufficient for resistance to be observed. However, in the presence of a single gene or gene complex which segregates independently of H-2, differential effects of various H-2 haplotypes can be seen. Resistance is radiation-sensitive and silica-insensitive and probably depends on active immune responses. The data also suggest that production by a hybrid of endogenous viral antigens with certain type-specific determinants shared with viral antigens expressed on the tumor may interfere with resistance. The mechanism for this is not understood but might involve tolerance, suppression, or enhancing antibody.