B-COMPLEX RECOMBINANTS AND SARCOMA REGRESSION - ROLE OF B-L B-F REGION GENES/

The anti-sarcoma response of three B complex recombinant haplotypes B- R1(F24-G23), B-R2(F2-G23), and B-R3(F2-G23) was investigated. In a pre liminary experiment, one male heterozygous for the B-R1 recombinant ha plotype and another heterozygous for the B-R2 recombinant haplotype we re each mated to females, some of which carried the respective recombi nant. The anti-sarcoma response of progeny carrying the B-R1 recombina nt differed significantly from that of progeny carrying the B-R2 recom binant. Subsequently, each of the three recombinant haplotypes was pla ced on each of four B haplotype complex backgrounds, and compared to B -G and B-L/B-F region controls on the same background haplotype. For e ach recombinant, significant differences in tumor growth were found be tween the recombinant and B-L/B-F control chickens on either one, two, or three of the four genetic backgrounds tested. For each recombinant , no differences were found between chickens carrying the recombinant and B-G region controls, which is further evidence that the gene(s) co ntrolling Rous sarcoma growth lies in or near the B-L/B-F chromosomal region. Moreover, although the B-R2 and B-R3 recombinants appear to be identical serologically, they differed significantly in tumor growth suggesting that the two haplotypes are genetically different.