Localization of keratin proteins in the human epidermis by a postembedding immunoperoxidase technique.

Individual keratin species were localized ultrastructurally to the tonofilaments and tonofibrils of the human epider-misusing a postembedding immunoperoxidase method. Low molecular weight keratin (45 kD) was localized primarily to the stratum basale and displayed a fine cytoplasmic staining of individual tonofilaments and some tonofibrillar staining. Higher molecular weight keratins (55 and 63 kD) were found predominantly in the suprabasal, differentiated squamous epithelial cells, staining tonofibrils with a web-like pattern. The technique utilized is suitable for studying the distribution of keratin proteins in normal and disease states.