Host genetics and resistance to acute Trypanosoma cruzi infection in mice. I. Antibody isotype profiles

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Abstract
Some strains of inbred mice survive acute infection with Trypanosoma cruzi while others die within a few weeks after infection. Mice which express B10 background genes and either the H-2q or H-2d haplotypes are resistant and survive. However, mice which share the B10 genetic background but express H-2k alleles die, usually within 4 weeks following infection. These data confirm that at least 1 gene in the major histocompatibility complex can determine whether an animal lives or dies during the acute phase. Expression of the H-2q haplotype on the B10 genetic background or in DBA/l mice is associated with resistance, but H-2q mice expressing the C3H background are susceptible. Therefore, at least I gene in the genetic background also influences resistance. Our data suggest that genes associated with resistance must be present in both the MHC and the genetic background or the animal will die. The isotypes and specificities of parasite reactive antibodies found in the serum of different inbred mouse strains were assessed during acute infection. Levels of IgM were higher in sera from mice which express the resistant B10 background than in sera from mice expressing the susceptible C3H background. Conversely, mice which share the C3H background genes produced high levels of anti-parasite IgG2a when compared to B10 congenic strains. Antigen specificity, however, may be influenced by both background and MHC genes, as congenic strains expressing different MHC haplotypes recognized different constellations of T. cruzi antigens. These data suggest a correlation between genes which influence antibody specificity or isotype and the genes which determine the ability of various inbred mouse strains to survive acute infection with T. cruzi.