Identification of two carbohydrate-specific erythrocyte agglutinins in the haemolymph of the protochordate Botrylloides leachii.

The haemolymph of the colonial ascidian Botrylloides leachii contains two haemagglutinins which have been termed HA-1 and HA-2 respectively. The HA-1 agglutinin is specific for guinea-pig erythrocytes, requires Ca2+ ions for its activity and has an apparent mol. wt. of about 200,000. It can be adsorbed by guinea-pig but not human, sheep, mouse or pigeon erythrocytes. The agglutination of guinea-pig cells is reversibly inhibited by various mono- and oligosaccharides, lactose and D-galactose being among the most effective of those tested. The HA-2 agglutinin is smaller (mol.wt. approximately 63,000) and agglutinates a variety of erythrocyte types, including those from the human, guinea-pig, mouse, sheep, pigeon and chicken. The agglutination of all these cells is inhibited by lactose. Data from sugar-inhibition and adsorption experiments indicate that the HA-2 agglutinins are homogeneous with respect to binding site specificity. Divalent cations are not required for activity.