Immunohistochemical localization of concanavalin A and wheat germ lectin receptors in the normal human spermatozoa

Abstract

A semiquantitative immunohistochemical technique for the detection of N-acetyl alpha-D-neuraminic acid, N-acetyl beta-D-glucosamine and its beta-(1 leads to 4)-linked internal chains, alpha-D-glucopyranosyl and alpha-D-mannopyranosyl and its alpha-(1 leads to 2)-linked internal chains and sterically related, nonreducing, end-chain residues of oligosaccharide chains of glycoproteins or glycolipids on the surface of membranes was developed using Con A and wheat germ lectins. When this method was applied to the localization of carbohydrate receptors on the membrane of the normal human spermatozoa, it was found that the Con A and wheat germ lectin receptors were mainly located in the equatorial and post nuclear cap with few receptors located in the acrosome and neck. None of them were found in the intermediate segment plus tail. Con A receptors were alpha-D-mannopyranosyl end-chain residues and wheat germ lectin receptors were N-acetyl beta-D-glucosamine (1 leads to 4)-linked internal chains. These groups occur together in the oligomannosidic type of N-glycosidic-linked oligosaccharide chains of glycoproteins and so the use of both lectins on desialycated membranes or on those which contain nonclustered N-acetyl neuraminic acid residues may be of help to localize this type of glycoprotein oligosaccharide chains. Con A receptors were not removed after proteases digestion, suggesting the possibility that they are part of intrinsic spermatozoal antigens.