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 Fcgamma receptors (FcgammaR), which are important for immunoregulatory functions. In this study we investigate FcgammaRIII expression on cultured human keratinocytes and upregulation by interferon-gamma. By real-time polymerase chain reaction, we show basal mRNA expression of both subclasses FcgammaRIIIA and FcgammaRIIIB, but after interferon-gamma treatment mRNA of FcgammaRIIIA and FcgammaRIIIB is increased 4.4 and 6.5 times, respectively. FcgammaRIII protein expression and its increase after interferon-gamma 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 FcgammaRIIIA and FcgammaRIIIB subclasses and their upregulation by interferon-gamma on human keratinocytes in vitro, and confirm FcgammaRIII protein expression by indirect immunofluorescence and by immunoblotting experiments.