[100 years of lectin research--a balance].

A hundred years of lectin research has led to the development of lectinology as an independent field of study. Although lectinology is in part related to immunology, fundamental differences exist. Lectins are important tools in biochemistry, histochemistry and clinical diagnosis. The essential in vivo function of lectins is to combine glycoconjugates. The function of lectins in microorganisms and in animals is partially known, whereas the function of lectins in plants is mostly unclear. Of special interest, now as before, are the toxic lectins of the ricin type consisting of an A-chain (N-glycosidase) and a B-chain (D-galactose-specific lectin).