HISTAMINE-RELEASE INDUCED BY GLUCOSE (MANNOSE)-SPECIFIC LECTINS ISOLATED FROM BRAZILIAN BEANS - COMPARISON WITH CONCANAVALIN-A

The histamine releasing properties of glucose (mannose)-specific lecti ns isolated from Brazilian beans was examined. The Canavalia brasilien sis, Dioclea rostrata, and Dioclea virgata lectins induced histamine r elease in rat peritoneal mast cells similar to concanavalin A. Less po tency and efficacy was observed for Canavalia maritima, Dioclea guiane nsis, and Dioclea violacea while very low activities were seen for the lectins from Dioclea grandiflora, Canavalia bonariensis, and Cratylia floribunda. The histamine releasing effect was quenched by higher dos es of D. virgata lectin similar to what was reported for concanavalin A. This effect was abrogated by increasing the concentration of calciu m in the incubating medium. As these above proteins have sites that bi nd calcium, higher doses of the lectins might withdraw the calcium whi ch is essential for the mast cell secretion.