Occurrence of natural antibody to the G (gross) leukemia antigen in mice.

Antibody with specificity for the G (Gross) leukemia antigen is frequently demonstrable in older normal C57BL/6 and C57BL/6 hybrid mice, and is occasionally present in mice of other genotypes. Mice of strains with a high incidence of leu kemia (G + strains) do not form G antibody. The pattern of oc currence of natural antibody in these various strains, and in various crosses, suggests that the capacity to produce G anti body plays an important part in the resistance of mice of certain genotypes to the induction of leukemia by naturally transmitted Gross virus. The high incidence of leukemia in strains of mice of susceptible genotype, on the other hand, appears to be associated with uninhibited replication of Gross virus and consequent im munologie tolerance. In segregating F2 and backcross popula tions derived from crosses between G + and G —strains, natural antibody was found in some mice of H-2bb and H-2kb genotypes, but not in H-2kk segregants. Thus the relative resistance to Passage A Gross virus shown by mice carrying H-2kb and H-2bb alÃ-eles,and the relative susceptibility of mice carrying H-2kk alÃ-eles,may have an immunologie basis.