Interaction of secretory immunoglobulin A antibodies withNaegleria fowleritrophozoites and collagen type I

Abstract

In this work, we analyzed the in vitro interaction of human secretory immunoglobulin A (sIgA) antibodies with Naegleria fowleri trophozoites and the capacity of these antibodies to inhibit amoeba adherence to collagen type I. We also studied N. fowleri antigens that are recognized by sIgA, using immunoblot assays. Immunocytochemical analysis of the interaction showed a redistribution of antigens on the surface of trophozoites by sIgA antibodies. Ultrastructural analysis of antibody–amoeba interaction showed that besides the patching and cap formation, parasites were capable of eliminating the antigen–antibody complex produced on the surface. sIgA antibodies were capable of inhibiting the in vitro adhesion of trophozoites to collagen type I. We suggest that nonsymptomatic infections by N. fowleri may stimulate a local specific immunity that prevents trophozoite adhesion and invasion of nasal mucosa.Key words: Naegleria fowleri, free-living amoebae, human antibodies, secretory IgA, mucosal immunity.