Lectins in fish skin: do they play a role in host-monogenean interactions?

Mucus samples from rainbow trout skin with or without infections by Gyrodac tylus derjavini were tested for the presence of lectins reacting with manno se, galactose and lactose. The samples inhibited the binding of biotinylate d lectins (from Canavalia ensiformis, Artocarpus integrifolia and Erythrina corallodendron, respectively) to microtitre plates with covalently bound c arbohydrates (mannopyranoside, galactopyranoside and lactose, respectively) . However, the inhibition of C. ensiformis and A. integrifolia lectins was slightly greater when mucus from infected (but recovering) fish was used, s uggesting an increase of mannose and galactose binding lectins in fish skin exposed to parasites. As mannose, galactose and lactose are present on the glycocalyx of Gyrodactylus derjavini, it is suggested that lectins could p lay a dual role in interactions between fish hosts and their monogenean par asites. Thus, recognition between parasite and host and also host responses towards parasite infections could both, at least partly, involve carbohydr ate-lectin binding.