F4/80 is a ~160 kDa transmembrane glycoprotein belonging to the EGF-TM7 family of G-protein-coupled receptors. F4/80 is considered a marker of choice for the identification of mature tissue macrophages, being broadly but variably expressed by this cell type in the liver (Kupffer cells), skin (Langerhans cells), bone marrow stroma, pancreas, thymus, spleen (red pulp), lung, and other tissues. It is also expressed by circulating monocytes, eosinophils and a subset of dendritic cells. F4/80 expression levels increase following activation of macrophages
F4/80 is reportedly the only macrophage marker suitable for distinguishing destructive from non-destructive inflammatory processes in the pancreas.