IMMUNOLOGICAL RELATIONSHIPS DURING PRIMARY INFECTION WITH HELIGMOSOMOIDES-POLYGYRUS - REGULATION OF FAST-RESPONSE PHENOTYPE BY H-2 AND NON-H-2 GENES

The inheritance of response phenotype to Heligmosomoides polygyrus was investigated in F1 hybrid progeny of fast and slow responder mouse st rains. The fast responses of SJL(H-2S) and SWR(H-2q) mice were mediate d by dominant genes complementing each other in F1 hybrids which lost worms earlier and produced faster parasite-specific IgG1 antibody resp onses than either parent. However, the response of F1 hybrids from cro sses of C57BL/10 (B10, H-2b) mice with either SJL or SWR differed from that of the parental strains and from each other: (B10 x SWR)F1 lost worms earlier than SWR whilst (B10 x SJL)F1 lost worms later than SJL mice. The F1 progeny of SJL mice with congenic strains B10.G (H-2q) an d B10.S (H-2S) lost worms as quickly as SJL. Therefore, the response p henotype mediated by the genome of SJL mice was unaffected by H-2 hete rozygosity (with H-2q) or homozygosity (H-2S) despite heterozygosity w ith B10 background genes, but was slowed significantly by heterozygosi ty with H-2b. All hybrids involving heterozygosity with B10, irrespect ive of MHC haplotype or background, failed to clear worms completely, in each case a proportion of mice harbouring residual worm burdens aft er loss of worms from parental strains.