IMMUNOPATHOLOGY OF TOXOCARA-CANIS AND ASCARIS-SUUM INFECTIONS OF THE EYE - ROLE OF THE EOSINOPHIL

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  • 1 January 1979
    • journal article
    • research article
    • Vol. 18  (11) , 1172-1184
Abstract
Intravitreal infection of guinea pigs with 2nd-stage T. canis larvae and 2nd- and 4th-stage A. suum larvae induced intraocular Ig[immunoglobulin]E antibodies [Ab] and dense eosinophil infiltration in the anterior chamber and throughout the uveal tract. The eosinophil infiltrate began within 1 day after infection and persisted for 51 days. By day 12 after intravitreal infection, the injected ascarid larvae were surrounded by granulomas which consisted almost entirely of eosinophils. Firm adherence of eosinophils to the parasite cuticle, morphologic alterations and degranulation of eosinophils with deposition of free eosinophil granules on the parasite surfaces, and ingestion of eosinophils and eosinophil granules by the parasite larvae were observed. Intravitreal injection of a soluble antigen derived from 3rd-stage A. suum molting to the 4th-stage in defined media in vitro induced intraocular IgE Ab and a diffuse ocular eosinophil infiltrate. Dense eosinophil infiltration of the choroid, not immediately adjacent to a parasite larva, was accompanied by destruction of the overlying outer retina, with cystic changes in the retina and between the retina and the choroid. Few eosinophils were observed within the retina and the retinal destruction may result from direct toxic action of constituents of the choroidal eosinophils. The eosinophil may be the principal effector cell in immunity to helminth infections and may be cytotoxic for the parasites. Possible mechanisms for the induction of the ocular eosinophil infiltrates and evidence for autotoxicity by eosinophils are briefly reviewed, and the potential roles of the eosinophil in the ocular response to helminth parasites are discussed.