The Nature and Mechanism of Immunity in Various Intestinal Nematode Infections

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  • Biological Laboratory, Rice Institute, Houston, Texas

Summary

There are two phases of immunity in intestinal nematode infections, (a) a general parenteral immunity stimulated mainly by metabolic products of growing and developing larvae during a period of parenteral migration or mucosal burrowing, and (b) a local intestinal immunity stimulated by metabolic products of adult reproducing worms. In worms like Nippostrongylus, Stongyloides, and Trichinella, which feed on intestinal mucosa as adults, the intestinal immunity plays a dominant and important part in the functional immunity of the host, causing a powerful and rapidly-developing resistance to reinfection, but against blood-suckers like hookworms and Haemonchus there is no effective local intestinal immunity. Reaction against these worms depends upon the less powerful and more slowly developing parenteral immunity, which becomes effective only after long-continued reinfection. Some Ascaridata, e.g., Ascaridia and Heterakis, stimulate a rapid and effective acquired resistance in spite of the fact that they are commonly thought to feed mainly on intestinal contents, suggesting that they may have some dependence on living mucosal cells throughout their lives and not merely during the period of initial burrowing.

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