FIGURE 1.

The origin of hepatic macrophage subsets in mice and humans. Hepatic macrophages are mainly comprised of KCs and MDMs. KCs are located in the sinusoid of the liver with a yolk sac or bone marrow origin. Infiltrating monocytes are categorized into 2 subsets: Ly6C^hi and Ly6C^lo monocytes, mainly derived from the bone marrow as well as the spleen. The peritoneal macrophages originating from the peritoneum also contribute to the infiltrating monocytes. Activated macrophages undergo differentiation or polarization into 2 distinct subtypes, namely M1 (proinflammatory) and M2 (prorepair). Abbreviations: MDMs, monocyte-derived macrophages; MHC, major histocompatibility complex.