Lectins and lectin-like molecules in lower plants. I. Marine algae (review)

Marine algae possess agglutinins, generally of unknown carbohydrate specificity, against a diverse array of erythrocytes but in a small number of species these haemagglutinins react with certain human blood group types. In seaweeds, lectins or lectin-like molecules are involved in gamete recognition and consequent reproductive cell fusion. Although some substances produced by algae are antiviral, antifungal, antibacterial, haemolytic and toxic, no similarity to mammalian immunoglobulins either structurally or physico-chemically has been observed for algal agglutinins. Whether such compounds have a defence or immune function and perform an antibody-like role to enable algal species to survive and counteract infections within their environment remains tentative.