Combination of immunological and lectin reactions in affinity histochemistry: proposition of the term affinitin

[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).

A method for the fine-structural demonstration of lectin receptors

A new two-step method using an Fc-fragment/ferritin conjugate as a marker for the visualization of lectin-binding sites on neuronal and other cell membranes is described. In this study of rat synaptosomes, three lectins were tested: concanavalin A, mistletoe lectin I and wheat germ agglutinin. The specificity of the method was proved by control experiments.

Mistletoe lectin I binding sites on the synaptosomes of the rat cerebral cortex

By means of combined lectinological and immunological methods were demonstrated mistletoe lectin I binding sites on rat cerebral cortex synaptosomes. The mistletoe lectin I binds specifically D-galactose. Galactosyl residues were established on the junctional and nonjunctional synaptosomal membrane, on the synaptic vesicles, mitochondria and on myelin contamination. The relative number of mistletoe lectin I receptors per unit area of synaptosomal membrane was calculated.