Lectin(from the Latin legere: to choose) is a sugar binding protein or glycoprotein of non-immune origin which agglutinates cells or precipitates glycoconjugates(1). Cell agglutination is a consequence of the formtion of numerous lectin bridges between surface oligosaccharide determinants on neighbouring cells.
Lectins exert a variety of remarkable biologic effects on cells: agglutination of erythrocytes and other types of cell, mitogenic stimulation of lymphocytes, generation of suppressor cells, mediation of Killing of target cells by lymphocytes and macrophages, enhancement of phagocytosis of yeasts and bacteria by macrophages, insulin-like effects on fat cells, toxicity to cells and animals, inhibition of growth and migration of tumor cells, induction of vacuole formation in macrophages, immunosuppressive effects in vivo, promotion of cell adhesion and spreading, induction of platelet release reaction, induction of histamine release from basophils and mast cells, induction of patching and capping of receptors on cell surfaces, peroxide release from macrophages, inhibition of endocytosis of lysosomal enzymes by cultured fibroblasts, inhibition of fungal growth, inhibition of fertilization of ovum by sperm, effect on aplastic anemia, anticytotoxic effect on nitrogen mustard and etc(2, 3).
By virtue of these characteristics, lectins have become powerful tools in biochemical and medical researches.
During the past decade, lectins have been found in a wide variety of plants, animals and microorganisms(4-7). Studies of the functions of lectins in plants have been reviewed by many authors(8-11). But research on animal lectins has only recently begun; consequently there are only limitted reviews(12-14) and moreover little is known about the lectins from marine animals(15-22).
During the past several years, we have concentrated our efforts on the isolation, purification and characterization of new lectins from marine invertebrates(23-29). And through these works, we could anticipate the possibility of application of lectins in life science, particularly in cancer research.
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