The relative importance of Ah versus H-2 genotype on Trichinella resistance following exposure to 3-methylcholanthrene.

The relative influence of Ah vs H-2 genotype on the outcome of Trichinella spiralis (Tsp) infections of mice was examined following methylcholanthrene (MC) treatment. Female mice of four inbred strains were treated with MC and infected 24 h later with Tsp muscle larvae. The strains, with their respective major histocompatibility complex (MHC) haplotype, aryl hydrocarbon hydroxylase responsiveness (Ah phenotype) and level of susceptibility to Tsp infection, were: C3HeB/FeJ (C3), H-2k, Ahb, Tsp susceptible; C57BL/10.BR (B10.BR), H-2k, Ahb, Tsp susceptible; C57BL/10.Q (B10.Q), H-2q, Ahb, Tsp resistant; and AKR/J (AK), H-2k, Ahd, Tsp resistant. The proliferative response of splenic lymphocytes to crude Tsp L1 stage antigen was significantly depressed in all MC-treated groups, with the exception of the B10.BR strain. MC administered at 40 mg/kg impaired the ability of C3 and B10.Q mice to eliminate adult worms. At 80 mg/kg, C3 strain mice were also impaired, as well as AK strain mice. The fecundity of female worms recovered from B10 or AK strain mice was not significantly altered by MC treatment, although female worms from treated C3 mice exhibited increased fecundity on day 9 post infection. Muscle larvae burdens of MC-treated B10 and C3 mice were elevated, while those of AK strain mice were unaffected. These data suggest that with acute exposures to MC, the immunogenetic resistance or susceptibility of a given mouse strain may have a more pronounced effect on immune depression and the severity of Tsp infection than does the Ah phenotype.