Intestinal immune responses of mammals to nematode parasites

Abstract

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. © 1989 by the American Society of Zoologists.