A LIPOPOLYSACCHARIDE-BINDING HEMAGGLUTININ WITH SPECIFICITY FOR ACETYLATED AMINOSUGARS IN THE SERUM OF THE HERMIT-CRAB DIOGENES AFFINIS (HENDERSON)

A naturally occurring hemagglutinin was detected in the serum of the h ermit crab Diogenes affinis, and its erythrocyte (RBC) binding activit ies, physicochemical properties, and carbohydrate binding specificity were characterized. Both the hemagglutination profile and the pattern of crossreactivity of the serum with different RBC types in cross-adso rption tests suggested a strong affinity of the serum agglutinin for r at RBC. Further analysis revealed that the agglutinin was specifically dependent on Ca2+ for its hemagglutinating activity and reversibly se nsitive to EDTA. The activity was found to be stable between pH 6.0 an d 7.5, heat-labile, and completely precipitable by ammonium sulphate o r TCA, suggesting the proteinaceous nature of the serum agglutinin. In hemagglutination-inhibition assays, the serum agglutinin of D. affini s showed a distinct and unique specificity for acetyl group-containing carbohydrates and glycoprotein. Furthermore, the hemagglutinating act ivity of the serum agglutinin was also inhibited by lipopolysaccharide from Salmonella abortus equi, which might indicate a significant role of humoral agglutinin in the immune response of crustaceans against b acterial infections. (C) 1994 Academic Press, Inc.