Gracilaria tikvahiae agglutinin. Partial purification and preliminary characterization of its carbohydrate specificity.

A potent agglutinin of rabbit and sheep red blood cells, obtained from the red alga Gracilaria tikvahiae, was purified by ammonium sulfate fractionation, ion exchange, gel filtration, and hydroxylapatite chromatography. Human A and B blood group erythrocytes were also agglutinated, whereas human O blood group erythrocytes were not agglutinated. The hemagglutination titer was not significantly affected by the addition of EDTA or the divalent cations Ca2+, Mg2+, or Mn2+. The carbohydrate specificity was characterized by hemagglutination inhibition using various monosaccharides, glycoproteins, and glycopeptides. The results suggested that the agglutinin has affinity for N-acetylneuraminic acid as well as glycoconjugates containing N-acetylneuraminic acid.

Inhibition of an anti-Pr1d cold agglutinin by citrate present in commercial red cell preservative solutions.

A patient with known cold autoimmune hemolyticanemia was admitted for surgery. Routine cold agglutinin evaluations, using commercial red cells (RBCs) in modified Alsever's preservative solution, revealed a cold agglutinin titer of 4 to 16. However, using RBCs washed four times with saline, a high-titer (greater than 2000 at 4 degrees C) cold autoagglutinin was demonstrated. The cold agglutinin was shown to be an IgM kappa paraprotein with anti-Pr1d specificity. The addition of Alsever's solution to washed RBCs inhibited the cold agglutinin. Each major component of Alsever's solution (neomycin, chloramphenicol, inosine, dextrose, and citrate) was tested individually; only citrate inhibited the patient's cold agglutinin. Various compounds structurally related to citrate were tested and found to cause various degrees of inhibition. The strongest inhibition correlated with the presence of either three carboxyl groups on molecules devoid of double-bonded carbon atoms or two carboxyl groups in cis configuration. A panel of 54 cold agglutinins, including 7 with anti-Pr specificity, was analyzed. None was significantly inhibited by Alsever's solution, although one with anti-Pr2 specificity was weakly inhibited. In summary, these studies describe an anti-Pr1d cold autoagglutinin that was inhibited by citrate in RBC preservative solutions. The failure to detect such a cold agglutinin can result from not washing RBCs free of citrate before testing.

Isolation of a keto sugar specific agglutinin from rat uterus.

A ketosugar-specific agglutinin has been identified and purified to apparent homogeneity by affinity chromatography from the three days post-coital rat uterus. This protein is not found in other stages of estrous cycle. The agglutinin is glycoprotein, moves as single band with molecular weight 37,000 in polyacrylamide gel electrophoresis and pI is 4.2. Among the ketosugars, fructose and ribulose effectively inhibit the agglutinin activity, beside these sugars, mannose, glucose, alpha methyl-mannoside and glucoside are also effective as potent inhibitors. Possible roles of this protein in pregnancy are discussed.

Induction of macrophage-mediated tumor lysis by an animal lectin, Sarcophaga peregrina agglutinin.

Several animal lectins, such as Sarcophaga peregrina agglutinin, Limulus polyhemus agglutinin, Helix pomatia agglutinin and Helix aspersa agglutinin, were tested for induction of tumor lysis mediated by macrophages. Among them, only S. peregrina agglutinin purified from the hemolymph of S. peregrina larvae lysed tumor cells in co-operation with macrophages from the peritoneal cavity of mice. S. peregrina agglutinin alone did not kill target tumor cells. Macrophages in the presence of this lectin could kill other syngeneic tumor cells. This lectin-dependent cytolysis by macrophages was inhibited by galactose, a sugar which is specifically recognized by S. peregrina agglutinin. These findings suggest that the animal lectin S. peregrina agglutinin is a ligand in macrophage-mediated cytolysis, inducing binding of effector macrophages to target cells which in turn triggers off lysis of the target cells.