Investigation on the occurrence of soluble lectins in mammalian nervous tissue extracts.

Five brain or retina crude extracts obtained from adult mammalians and nine fractions of brain extracts prepared by chromatography were screened for their lectin activities. All crude extracts and several fractions contained agglutinins reacting with neuraminidase-treated rabbit red blood cells. Hemagglutination activity varied widely with the method of preparation of the extracts. Hemagglutination inhibition tests were carried out to look for possible differences in the specificities of the agglutinins. All were found to be D-galactosyl specific. Each crude extract was found to contain a second lectin activity, which was detected using ethanol-treated rabbit erythrocytes known to react with heparin-binding lectins. Hemagglutination and inhibition studies showed that they completely differ from the galactoside-binding lectins detected previously. The possible functions of these lectins are discussed.