IMMUNOHISTOCHEMICAL LOCALIZATION OF KERATIN IN NORMAL HUMAN-TISSUES

Abstract

Immunohistochemical identification of intracellular keratin was achieved using an indirect antibody technique on paraffin-embedded human tissue. A study of numerous tissues confirms that keratins are abundant in all layers of squamous epithelia, in the ducts of epithelial-derived glands and in the epithelia of the respiratory and urinary tracts. By using an immunoperoxidase technique which offers increased histologic resolution, the basal or reserve cells of the tracheal, bronchial, prostatic and cervical gland epithelia are shown to be the predominant keratin-containing cells in these tissues. The normal differentiation of basal cells into nondividing, superficial columnar cells is accompanied by the loss of cytoplasmic keratin proteins. Foci of epithelial squamous metaplasia stain intensely with antikeratin antibodies and presumably represent an exaggerated proliferation of the keratin-containing basal cells. Alveolar respiratory epithelium, acinar cells of various glands and many mesodermal tissues (muscle, hematopoietic and lymphoid tissue, nerve and connective tissue) were devoid of keratin proteins. The ability to identify keratin proteins within fixed, embedded tissue (including those known to lack tonofilament bundles) may be useful in the study of tissue histogenesis and carcinogenesis and in the pathologic assessment of poorly differentiated malignant neoplasms and tumors of controversial cellular origin.