Lectins in the hemolymph of a starfish, Asterina pectinifera: Purification and characterization

Abstract

Naturally occurring lectins or receptorspecific proteins have been reported in the hemolymph and various tissue extracts of marine invertebrates (1,2). There has been extensive discussion on the physiological significance of lectins. In the case of invertebrate humoral lectins, it has been postulated that one of their physiological functions is recognition of self from in cooperation with cellular and humoral defense processes such as vertebrate antibodies (3,4). The presence of multiple lectins in the hemolymph in the arthropods and mollusks (5-9) is one piece of important evidence in support of the hypothesis that considers the lectins to be recognition factors in defense procedures since it is not readily acceptable that only single molecular species of lectin distinguish nonself from self. The opsonizing effects of humoral lectins or cell membrane-associated lectins have also been demonstrated in mollusks and arthropods (10-14). In the course of our screening for lectins in marine invertebrates, we observed the presence of lectins that agglutinated mammal erythrocytes and a marine bacterium in the hemolymph of a starfish, Asterina pectinifera. An attempt was made to purify the active components from the hemolymph. The present article deals with the agglutinating activity of the starfish hemolymph and the properties of a lectin, APL-R, that preferentially agglutinated rabbit erythrocytes from A. pectinifera hemolymph.