Carbohydrate-Bearing Cell Surface Receptors Involved in Innate Immunity: Interleukin-12 Induction by Mitogenic and Nonmitogenic Lectins

Based on the observation that pathogen-derived lectins play an important role in cell adhesion and invasion, we examined the possible role of host carbohydrate-bearing molecules in inducing the secretion of IL-12, a crucial proinflammatory cytokine. The ability of 12 plant lectins to recognize and stimulate naive murine mononuclear cellsin vitrohas been characterized in this study. Mitogenic lectins (comprising Con A, PHA, PSA, and LCA) were found to induce the secretion of multiple cytokinesin vitro,including IL-2, interferon (IFN)-γ, and IL-12. Of interest, WGA, a nonmitogenic lectin unable to promote IL-2 secretion, was found to induce IL-12 and IFN-γ production in a T and B cell-independent fashion. The functional properties of WGA were inhibited byN-acetylneuraminic acid andN,N′-diacetylchitobiose. WGA therefore represents a potentially useful tool for the study of membrane glycoproteins involved in the early proinflammatory response characteristic of innate immunity.