Relevance of plant lectins in human cell biology and immunology.

Protein-carbohydrate interactions are used for intercellular communication. Mammalian cells are known to bear a variety of glycoconjugates. Lectins, first discovered in plants, are proteins which can specifically bind carbohydrates. Given the high affinity of plant lectins for carbohydrates, they have always been important as molecular tools in the identification, purification and stimulation of specific glycoproteins on human cells. Lectins have provided important clues to the repertoire of carbohydrate structures in animal cells. The discovery of plant lectins gave a great impulse to modern glycobiology. They represent important biochemical reagents for numerous applications in the biomedical field and in research. Sequence determinations and structural characterization helped to understand the mechanism of action in many biologic systems. Plant lectins have been fundamental in human immunological studies because some of them are mitogenic/activating to lymphocytes. Understanding the molecular basis of lectin-carbohydrate interactions and of the intracellular signalling evoked holds promise for the design of novel drugs for the treatment of infectious, inflammatory and malignant diseases. It may also be of help for the structural and functional investigation of glycoconjugates and their changes during physiological and pathological processes.