Immunogenetic and evolutionary influences on the host-parasite relationship.

Immunogenetic aspects of the host-parasite relationship between the laboratory mouse and the parasitic nematode Trichinella spiralis are reviewed. Variation in the capacity of hosts to express an effective protective immunity is associated primarily with variation in inflammatory responsiveness. Analysis of the contributions of T lymphocytes, cytokines, and myeloid precursor populations to variation in one particular inflammatory component, eosinophilia, is described. Variation in parasite immunogenicity at the level of host responsiveness to different parasite isolates is described briefly. Variations in host-protective immunity, immunopathology, and parasite immunogenicity are discussed in terms of evolutionary pressures selecting for optimal host and parasite survival in a stable symbiosis.