© 1989 by The Society for Integrative and Comparative Biology
Intestinal Immune Responses of Mammals to Nematode Parasites1
U.S. Department of Agriculture, Agricultural Research Service, Helminthic Diseases Laboratory, Livestock and Poultry Sciences Institute Beltsville, Maryland 20705
Departments of Pediatrics and Medicine, Uniformed Services University of the Health Sciences Bethesda, Maryland 20814
In mammals, intestinal immunity to gastrointestinal nematode parasites can result in a dramatic expulsion of resident adult worm populations from the intestine and exclusion of subsequent infections. Although immunity requires specific parasite-antigen induction, the expression of host resistance can be a product of both specific and nonspecific effector elements. T lymphocytes, through the action of cytokines, regulate the differentiation of certain classes of B lymphocytes and antibody producing plasma cells, as well as cells of myeloid origin that are involved in inflammation. Because inflammatory processes can function non-specifically against parasites in the intestine, they can be involved not only in host resistance to a homologous parasite infection, but also in cross-resistance to immunologically unrelated parasites. Thus, knowledge of the events necessary to prime the intestinal immune system of a naive host to a particular parasite could result in an understanding of how resistance might be induced to a variety of parasitic infections.
This article will show that generically distinct gastrointestinal parasites, with very different life cycles, can induce similar mammalian host responses. Yet the resolution of experimental infection with a particular parasite species can be quite different among various host species. In addition, the effect of T cell regulation of mast cells, eosinophils and immunoglobulin E on intestinal immunity and host cross-resistance to parasitic infection will be discussed.