F4/80, also known as EMR1 or Ly71, is a 160 kDa glycoprotein belonging to the epidermal growth factor (EGF)-transmembrane 7 (TM7) family. It is widely used as a murine macrophage marker. F4/80 is expressed on most tissue macrophages, including those in the lung, intestine, peritoneal cavity, thymus, and splenic red pulp, as well as Kupffer cells, Langerhans cells, microglia, and certain dendritic cell subsets. It is notably absent on macrophages residing in the T-cell areas of the spleen, lymph nodes, and Peyer's patches. Although the biological ligand for F4/80 has not yet been identified, this molecule has been reported to be required for the induction of CD8 T cell-mediated peripheral tolerance.
