Applications

Lectins are widely employed in research for diverse purposes, primarily those in which detection, identification and functional evaluation of carbohydrates is needed, and are also making a mark on medicine (Table 8.1) (Gabius, H.-J. & Gabius, 1993; Goldstein et al., 1997; Rhodes, J. M. & Milton, 1998). They offer many advantages, including ready availability, distinct specificity, and high stability. Even more important is the fact that their reactions with soluble substances and cells can be reversed by simple sugars. The specific interaction of a substance or cell with a lectin may be taken as evidence that it contains carbohydrates. Thus, lectin binding has frequently been used to demonstrate that membrane receptors for many hormones, growth factors, neurotransmitters and toxins are glycoconjugates. Studies with lectins have been largely responsible for the realization that carbohydrates play a key role in cell recognition (Sharon & Lis, 1989; Sharon, 1993), and for expanding the understanding of tissue-bound carbohydrates in histology and histopathology, both at the light and electron microscope level (Ewen, 1998). A new and promising application is lectin replacement therapy for the treatment of patients suffering from a lectin deficiency disease (Valdimarsson et al., 1998; Kilpatrick, 2002b).

In addition to exogenous lectins, endogenous, membrane-bound lectins are being tested for experimental targeting of drugs, enzymes, nucleic acids, genes and other agents to cells. An impressive example of such application is the treatment by enzyme replacement therapy of patients with Gaucher disease, who lack ß-glucocerebrosidase.