Epidermal Intercellular Staining with Fluorescein-Conjugated Phytohemagglutinins

Fluorescein-conjugated phytohemagglutinins, Concanavalin A and Phytohemagglutinin P were used to stain frozen-cut sections of human skin to determine the presence and distribution of carbohydrate-containing substances in the epidermis. An intercellular staining pattern was observed which appeared identical to that found in various forms of pemphigus. The intercellular staining could be inhibited, or abolished, by α-methyl-D-mannopyranoside or α-methyI-D-glucopyranoside in the case of Concanavalin A, and by N-acetyl-D-galactosamine in the case of Phytohemagglutinin P, but not by a variety of other monosaccharides tested. A similar pattern of staining could be produced in vivo in mouse and guinea-pig skin by intradermal injection of fluorescein-conjugated Concanavalin A. Staining with fluorescein isothiocyanate alone produced a staining pattern which was a negative image of that seen with the fluorescein-conjugated phytohemagglutinins, namely cytoplasmic staining, but absent intercellular staining.