The Role of Eosinophils in Immunity to Parasites: An Introduction

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  • Department of Medicine, Harvard Medical School, Robert B. Brigham Hospital, Boston, Massachusetts 02115

Although the association of eosinophils with many helminthic infections is not new, their role as bona fide effector cells in the immune attack on the parasite is. New evidence comes from studies discussed earlier in which it was shown, in vitro, that human eosinophils will mediate antibody-dependent damage to schistosomula of Schistosoma mansoni; the evidence was supported by in vivo studies which demonstrated that depletion of eosinophils by anti-eosinophil serum would abolish established immunity to cercarial challenge in mice. Other studies have shown that eosinophils are intimately involved in the inflammatory reactions around schistosomula at the site of cercarial challenge in an immune animal and also around schistosomula in the lung when these organisms have been injected intravenously into immunized mice. In addition to their active role against the larvae, eosinophils have been shown recently to destroy Schistosoma mansoni eggs in vitro, and are found in abundance in granulomas induced by eggs from Schistosoma mansoni.