Mechanism of eosinophilia in angiostrongyliasis cantonensis

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This study was performed to determine the mechanism of eosinophilia and the possible roles of the eosinophils in angiostrongyliasis cantonensis. The results obtained are summarized as follows: 1. The excretory/secretory (E/S) products of the young adult worms of Angiostrongylus cantonensis contain a major factor(s) responsible for inducing eosinophilia in the nonpermissive, guinea pig host with pulmonary arterial transfers of the worms. Such a factor(s) for the permissive rat host would possibly be associated with the eggs or lst-stage larvae. T cell-independency of the eosinophilic response to young adult worm extracts in the nonpermissive mouse host implies the presence of a direct eosinopoietic activity in the extracts. 2. Guinea pig-eosinophils strongly respond to the eosinophil chemotactic (EC) substance from adult worms both in vitro and in vivo, but rat-eosinophils failed to do so. A study is now underway to determine whether some receptors specific for the EC substances are pre … More sent on the guinea pig-eosinophils and also to determine whether eggs and larval stages have an EC activity. 3. When mediastinal lymph-node cells and splenic cells from the guinea pigs transferred with the young adult worms 5-14 days earlier were stimulated in vitro by young adult worm antigen, they generated and released an eosinopoietic factor(s) into the media. The factor is nondialysable and more than 10000 in molecular weight. Although the liquid marrow culture has so far failed to reveal the direct eosinopoietic activity of the somatic and E/S antigens of the young adult worms, soft-agar cultures are now in progress to determine the presence or absence of this activity. 4. Mice infected with A. cantonensis induced pleocytosis and eosinophilia in the cerebrospinal fluid (CSF), both of which were of T cell-dependence. The recovery of viable worms from the brains abruptly decreased in accordance with this CSF eosinophilia, suggesting the possible association of the eosinophilia with worm killing. An ultrastructural study revealed degraunlative and other changes in CSF eosinophils, e.g., the decrease in granule numbers and the appearance of small and round-shaped granules, suggesting the activated status of the cells. CSF eosinophils generated superoxide anion following the stimulation with PMA and digitonin. The present study is also suggestive of the possibility that young adult worm antigen is capable of stimulating <O_2> generation of the cells. A further study is required to determine why the rat host fails to develop CSF eosinophilia in spite of the presence of T cells in this animal. Less