Ultrastructural Localization of Keratin Proteins in Human Skin Using Low-temperature Embedding and the Protein A-gold Technique

Human skin was embedded in Lowicryl K4M and keratin proteins were localized by incubation with antikeratin antisera, followed by protein A-gold. The antikeratin antisera labeled all intermediate filament (tonofilament) structures in all layers of the epidermis. The association of keratin filaments with hemidesmosomes, desmosomes, and keratohyaline granules was clearly visualized. Desmosomes and keratohyaline granules were not labeled by the antikeratin antisera. No nonfilamentous structures were labeled. The technique described is suitable for studying the distribution of keratin filaments in normal and diseased tissue.