A study of a subpopulation of classically activated CD163+ macrophages was conducted. When stimulated by interferon (IFN) gamma, many genes upregulated in macrophages were found in psoriatic skin. These included HLA-DR, Mx1, CXCL9 and STAT1. CD163+ macrophages released interleukin (IL) 23p10, IL-12/23p40 in addition to tumor necrosis factor (TNF) and inducible nitric oxide synthetase (iNOS). Thus CD163 is a superior proxy marker of macrophages and identifies a subpopulation of classically activated cells. The key inflammatory products released likely contribute to the pathogenic inflammation in psoriatic skin (Fuentes-Duculan, J. et al. J Invest Dermatol 2010, 130: 2412).