Enhanced Inflammation to Brugia malayi Microfilariae in Ferrets Infected with Trichinella spiralis

Abstract

Intravenous (i.v.) injection ofmicrofilariae (mf) ofB. malayi in the ferret (Mustella putoriusfuro) has proven to be a convenient experimental method for study of the pathogenesis of occult filariasis. Following i.v. injection of mf, ferrets develop eosinophilia, immune clearance of circulating mf, and inflammatory responses to mf characteristic of tropical filarial eosinophilia or the Meyers-Kouwenaar (MK) syndrome of occult filariasis in man (Thompson et al., 1985, Experimental Parasitology 60: 181-194). Lesions visible on the surface of the liver, principally abscesses ofeosinophils measuring 1-2 mm in diameter, have been used to evaluate the inflammatory reactivity to mf. The number of lesions that develop following i.v. injection of mf is positively correlated with the level of peripheral blood eosinophils, but the relationship of lesion development to immune responses or hypersensitivity remains unclear (Thompson et al., 1985, loc. cit.). A preliminary observation indicated that Trichinella infection in ferrets induced eosinophilia and an enhanced inflammatory reaction to injected mf without evidence of cutaneous hypersensitivity to antigens ofmf. The objectives of the present study were to confirm the enhanced inflammatory reactivity to mf induced by Trichinella infection and to characterize the cellular and immune responses to mf in these ferrets which, it was considered, could help clarify mechanisms active in the pathogenesis of occult filariasis. The experimental procedures and immunologic assays have been described previously (Thompson et al., 1985, loc. cit.; Thompson et al., 1986, Zeitschrift fur Parasitenkunde 72: 525-535). To confirm that Trichinella infection altered