Cytokeratin 15 (C-term)

A number of human cytokeratins are expressed during the development of stratified epithelia from one-layered polar epithelia and continue to be expressed in several adult epithelial tissues (1). Cytokeratin 15 (CK15) is a type I keratin without a defined type II partner whose expression in epidermal diseases has not been investigated. A monoclonal antibody raised against the last 17 amino acids of the CK15 polypeptide show that CK-15 is expressed primarily in the basal keratinocytes of stratified tissues, including the fetal epidermis and fetal nail. Although CK-15 in normal hair follicles was virtually absent from hair bulbs, it was expressed by a subset of keratinocytes in the outer root sheath (2). In human conjunctival epithelium, strong expression of CK-15 was observed in basal cells, whereas CK19 was expressed in both basal and suprabasal layers. Although the expression of K15 and K19 differ in humans and mice, specific staining patterns can be used to characterize the epithelial phenotype in normal and diseased ocular surface (3).