A comparative study on the specificity of Androctonus australis (Saharan scorpion) and Limulus polyphemus (horseshoe crab) agglutinins.

The specificities of Limulus polyphemus and Androctonus australis sera were compared by agglutination and agglutination-inhibition micromethods with human untreated and enzyme-treated peripheral blood cells (erythrocytes, normal lymphocytes and chronic lymphocytic leukemia lymphocytes). Androctonus sera give higher titers than Limulus sera with erythrocytes and lymphocytes. Both sera show more avidity for leukemic than for normal lymphocytes. Limulus sera fail to agglutinate neuraminidase-treated cells but Androctonus sera react with untreated and neuraminidase-treated erythrocytes at the same degree. Sialyl-lactose is the best inhibitor for Androctonus sera, followed by N-acetylneuraminic and N-glycolylneuraminic acids, glucuronic and galacturonic acids, N-acetyl-D-glucosamine and N-acetyl-D-galactosamine. The amounts of inhibitor required depend upon the particular cell and enzyme treatment: agglutination of neuraminidase-treated erythrocytes by Androctonus is inhibited by lower concentrations of the same compounds that inhibit untreated erythrocytes agglutination. Results suggest that although Limulus and Androctonus have specificity for sialic acid containing compounds, on the cell surface, the Limulus receptors might be different from Androctonus receptors.