Ultrastructural and morphometric analyses of eosinophils from the cerebrospinal fluid of the mouse and guinea-pig infected with Angiostrongylus cantonensis

Guinea-pigs infected with Angiostrongylus cantonensis developed pleocytosis and eosinophilia in the cerebrospinal fluid (CSF) at day 12 post-infection (p.i.), showing a peak response at day 20 p.i., followed by a gradual reduction. Ultrastructural observations on CSF eosinophils from infected mice and guinea-pigs revealed various signs of eosinophil degranulation after day 14 p.i., suggesting the exocytosis of lysosomal material. Morphometric analysis indicated that CSF eosinophils after day 22 p.i. contained fewer granules as well as smaller granules than those at days 14-20 p.i. These data suggest that CSF eosinophils release granule constituents into the outside of the cells and these secretion products could interact with the intracranial worms and are probably related to worm death. As degenerative atrophy or partial loss of Purkinje cells and the spongy vacuolation of the white matter were noted in the cerebellum of infected mice, it was suggested that CSF eosinophils could be a possible cause of neurological disorders in angiostrongyliasis cantonensis.