Monoclonal antibodies to rat Kupffer cells. Anti-KCA-1 distinguishes Kupffer cells from other macrophages.

Two monoclonal antibodies, anti-KCA-1 and anti-KCA-2, directed against rat Kupffer cells (hepatic sinusoidal macrophages) were developed. Immunohistologic studies of the liver and analysis of isolated hepatic cells by immunofluorescence and flow cytometry showed that the reactivity of these antibodies was restricted to macrophages. Both KCA-1+ and KCA-2+ cells were located predominantly in the periportal region; in contrast, Ia+ sinusoidal cells were located primarily in the centrilobular region. Macrophagelike cells within the portal tracts expressed KCA-2 but not KCA-1. These findings indicate the presence of heterogeneity within the macrophage population of the liver. Anti-KCA-1 reactivity appeared to be almost entirely restricted to Kupffer cells; only a few macrophages in the thymus and a small number of cells in the bone marrow expressed KCA-1. In contrast, KCA-2 was more widely distributed; splenic, lymph node, and intestinal macrophages were intensely stained with anti-KCA-2. These studies indicate that KCA-1 is a marker of Kupffer cells.