FcγRIII expression on cultured human keratinocytes and upregulation by interferon-γ

Abstract

Keratinocytes of human epidermis are actively involved in inflammatory and autoimmune reactions of the skin and interact with resident or infiltrating immunocompetent cells via cytokines, chemokines, and intercellular adhesion mechanisms. Most immunocompetent cells have been reported to express Fcγ receptors (FcγR), which are important for immunoregulatory functions. In this study we investigate FcγRIII expression on cultured human keratinocytes and upregulation by interferon-γ. By real-time polymerase chain reaction, we show basal mRNA expression of both subclasses FcγRIIIA and FcγRIIIB, but after interferon-γ treatment mRNA of FcγRIIIA and FcγRIIIB is increased 4.4 and 6.5 times, respectively. FcγRIII protein expression and its increase after interferon-γ treatment were shown on cultured human keratinocytes by indirect immunofluorescence. In immunoblotting experiments, a bonified anti-CD16 antibody revealed reactivity to a polypeptide of 50-65 kDa on lysates of treated and untreated keratinocytes. In summary, we demonstrate expression of mRNA specific for the FcγRIIIA and FcγRIIIB subclasses and their upregulation by interferon-γ on human keratinocytes in vitro, and confirm FcγRIII protein expression by indirect immunofluorescence and by immunoblotting experiments.