Immunity in mammals to helminths of the circulatory and lymphatic systems, emphasizing nonhuman primate models and their comparison to human infections and rodent models

Abstract

The host-parasite relationship of intravascular helminths in mammalian hosts is complex, consisting of several interrelated aspects. These organisms are often very long lived in these hosts that possess highly evolved immune systems, which implies the existence of mechanisms in these complex parasites for evading the immune response. On the other hand, mammalian hosts appear to be very successful in limiting their worm burdens, mainly by preventing reinfection. Thus, a balance between host and parasite is often achieved. This balance extends to the immunopathological consequences of the infections as well. Especially in the schistosomes, where relatively more is known about immunopathology, it is becoming increasingly apparent that immunopathological reactions to the eggs are multifunctional and paradoxical: they cause disease, they limit disease, and they even serve the schistosome by making possible the escape of its eggs, laid deep within the tissues, from the host's body to propagate the life cycle. The comparative approach, using different species of schistosomes and filarids in different mammalian hosts, has proved to be valuable for understanding the immunological basis of these complex relationships. The knowledge gained from these model systems is already being vigorously applied to the human diseases, two of the great scourges of the tropics, schistosomiasis and lymphatic filariasis, to the end of their eradication from the earth by mass immunization. © 1989 by the American Society of Zoologists.