Partial characterization of a natural agglutinin in the hemolymph of the lobster, Homarus americanus

Partial characterization of a natural agglutinin in the hemolymph of the lobster showed: (1) Calcium ion stabilized the agglutinin against inactivation at moderate (35–45°C) temperatures as well as against a reversible increase in activity at nonphysiological pH levels (pH 6 and 9). (2) Serum frozen at ?20°C in the absence of calcium showed an increase in agglutinin activity. (3) Heat inactivation curves indicated a single component for the agglutinin. (4) Heat inactivation destroyed the ability of the agglutinin to be adsorbed to the erythrocyte antigen. (5) The chemical nature of the antigenic reactive site differed with the species of erythrocyte tested; D-glucosamine blocked or inhibited adsorption of the agglutinin to erythrocytes of most species tested. (6) In vivo the agglutinin is located in the hemocytes.