Heterogeneous humoral and hemocyte-associated lectins with N-acylaminosugar specificities from the blue crab, Callinectes sapidus Rathbun

Callinectes sapidus serum and hemocyte microsomal fraction agglutinated a panel of untreated and enzyme treated vertebrate erythrocytes and cultured lymphoid cell lines. Crossed absorption experiments suggested the presence of multiple specific lectins in the serum. The microsomal fraction showed a 35-fold increase in specific activity when compared to the hemocyte lysate suggesting that hemocyte lectins are membrane-associated. Agglutination by serum and hemocyte lectins was inhibited by low concentrations of N-acylamino compounds including sialic, N-acetylmuramic and N-acetylglutamic acids, GalNAc, GlcNAc, ManNAc, and glycoproteins and polysaccharides which contain these carbohydrates: bovine submaxillary mucin, human orosomucoid, porcine stomach mucin and colominic acid. Hemagglutination by lectins of both serum and hemocyte microsomal fraction required divalent cations as suggested by the reduction in hemagglutination titer in the presence of the chelators EDTA, EGTA, CDTA and citrate.