Applications of immunocolloids in light microscopy. II. Demonstration of lectin-binding sites in paraffin sections by the use of lectin-gold or glycoprotein-gold complexes.

A new procedure is presented for the light microscopic demonstration of specific sugar sequences of oligosaccharides in glycoconjugates by lectins combined with the colloidal gold marker system. Tissue sections from aldehyde-fixed and paraffin embedded rat kidney were stained either in a one-step method with lectin directly bound to particles of colloidal gold or in a two-step method using non-labeled lectin and glycoprotein labeled with colloidal gold. In both methods the presence of lectin-binding sites in the tissue sections is revealed by the appearance of a red coloration that is due to the accumulation of gold particles. The high specificity of the technique is combined with a good sensitivity and resolution as demonstrated by a differential plasma membrane staining in renal epithelial cells. The lectin-gold or glycoprotein-gold complexes remain stable for months and produce a permanent nonbleaching staining.