Inhibitory effect of wheat germ agglutinin on mouse mast cell adhesion to fibronectin

Background: Mast cells play a critical role in allergic and inflammatory re sponses. The interactions between these cells and extracellular matrix comp onents influence the distribution of mast cells in tissues and their biolog ical responsiveness. It has been reported that the lectin wheat germ agglut inin (WGA) inhibits mast cell mediator release. We decided to investigate w hether adhesion to fibronectin (FN), another mast cell function, which is u pregulated following Fc epsilon RI cross-linking, is also inhibited by WGA. Methods: Mouse bone-marrow-derived mast cell line MCF5/L was used. For Fc epsilon RI-dependent mast cell activation, MCP5/L cells were sensitized wit h mouse IgE antibodies. WGA was added to cell suspensions simultaneously wi th a challenging agent and, after an appropriate incubation period, P-hexos aminidase release and adhesion to FN were determined. Results: Both Fc epsi lon RI cross-linking-dependent mast cell adhesion to FN and mediator releas e were dose-dependently inhibited by WGA; however, the lectin concentration s required to induce maximum inhibition of adhesion were significantly lowe r. Furthermore, WGA inhibited phorbol-myristate-acetate- and A-23187-mediat ed mast cell adhesion to FN, i.e. processes that do not engage Fc epsilon R I. The effect of WGA on Fc epsilon RI-mediated secretion was reversed by Gl cNAc. In contrast, combination of GlcNAc and NeuNAc or N,N'-diacetylchitobi ose was required to reverse the inhibitory effect of WGA on mast cell adhes ion. Conclusion: The characteristics of WGA-mediated inhibition of MCP5/L m ast cell adhesion to FN suggest that mast cell integrins are targets of the inhibitory action of WGA and the sugar moieties on these receptors might b e important for receptor function. Copyright (C) 2000 S. Karger AG, Basel.