Lectin-binding ability of immunoglobulin E and its participation in triggering of mast cells

Eleven purified lectins were compared in their IgE-precipitating, mast-cell-degranulating and histamine-releasing activity and in eliciting skin allergic reactions in atopic or normal people. A significantly positive relationship could be proved between their IgE-precipitating activity and degranulation of IgE-sensitized rat mast cells. A similar and often significant relation was observed in skin reactions and histamine released from human leukocytes. Soybean lectin reacted with concanavalin A by a precipitation line in coalescence with the IgE showing the possibility of a common structural component. Correlation tests between different lectins show that all but three elicit the cell activation by similar ways, but different from IgE antiserum. Soybean lectin, Triticum vulgare and Vicia cracca reacted in other ways and correlated better with histamine release caused by the IgE antiserum. A certain degree of the heterogeneity in the IgE sugar component together with the complexity of the lectin structure may be responsible for a wide mode of activation on cell membranes. The significance of this non-immunological binding for sensitization, natural desensitization and cell regulation by physiological histamine release was discussed.