Immunohistochemical localization of parathyroid hormone-related protein (PTHRP) in normal human skin

Human keratinocytes secrete large amounts of a parathyroid hormone-related peptide (PTHRP) in vitro. Because recent studies indicate that PTHRP could have a number of autocrine or paracrine functions in the skin, localization of this peptide in vivo is important. A monoclonal and two affinity-purified polyclonal antibodies were employed to locate PTHRP in normal human skin and cultivated human keratinocytes. PTHRP is present throughout the viable portion of the epidermis, in adnexal epithelial cells, and in all cultivated keratinocytes. These findings do not support the provocative suggestion that PTHRP is a marker for squamous differentiation.