The use of lectins to study normal differentiation and malignant transformation.

Lectins are polypeptides that specifically recognize carbohydrate residues of glycoproteins and glycolipids. They can be extracted from plants, invertebrates and vertebrates. The binding between lectins and carbohydrate moieties can be blocked by the inhibitory sugar for which the lectin is specific. In analogy to antibodies, lectins can be used to analyse cell surface determinants. Thus, differentiation of cells, in particular of immunocytes, has been studied and lectin receptors are now important markers for distinguishing different developmental stages of T-lymphocytes. In consequence, premature, but already committed, T-cells can be eliminated from human bone marrow by means of lectins prior to transplantation in order to avoid graft-versus-host reactions. Moreover, it has been shown that malignant cells can be distinguished from their non-malignant counterparts by the profile of lectin receptors on their surface. This had led to the use of lectin binding sites as tumour markers in lymphomas and carcinomas.