Production of reactive oxygen species by hemocytes of Biomphalaria glabrata: carbohydrate-specific stimulation

Recognition of specific carbohydrate structures, which occur commonly on th e surfaces of invading pathogens, is thought to elicit internal defense mec hanisms in invertebrates. To investigate the nature of carbohydrates that e voke a defensive response in hemocytes of the gastropod Biomphalaria glabra ta, we tested eight different carbohydrates, conjugated to bovine serum alb umin (BSA), for generation of reactive oxygen species (ROS). Six of the car bohydrate moieties tested are thought to be present on the S. mansoni sporo cyst surface (mannose, galactose, fucose, N-acetyl-glucosamine, N-acetyl-ga lactosamine, and lactose); the other two carbohydrates tested were glucose and melibiose. ROS generation was measured using the fluorescent probe - 2' ,7'-dichlorofluorescein-diacetate (DCFH-DA). Hemocytes were derived from tw o different strains of B. glabrata: one of the strains used (MO) is suscept ible to infection by the trematode Schistosoma mansoni (PR-1 strain), while the other snail strain (13-16-R1) is resistant to infection with PR-1. Thr ee of the BSA-carbohydrate conjugates (BSA-galactose, BSA-mannose, and BSA- fucose). stimulated generation of reactive oxygen species in the molluscan hemocytes. The responses of the hemocytes were similar whether they were de rived from susceptible or resistant snails. If the carbohydrate structures we found, to stimulate ROS generation are involved in parasite recognition, our results suggest that parasite killing may involve either qualitative d ifferences in production of reactive oxygen species, or additional factors. (C) 2000 Elsevier Science Ltd. All rights reserved.