Kupffer cell

Overview
Kupffer cells, also known as Browicz-Kupffer cells, are specialized macrophages located in the liver that form part of the reticuloendothelial system (aka: mononuclear phagocyte system). The cells were first observed by Karl Wilhelm von Kupffer in 1876. The scientist called them "sternzellen" (star cells or stellate cells) but thought falsely that they were an integral part of the endothelium of the liver blood vessels and that they originated from it. In 1898, after several years of research, Tadeusz Browicz, a polish sciencist, identified them correctly as macrophages.

Their development begins in the bone marrow with the genesis of promonocytes and monoblasts into monocytes and then on to peripheral blood monocytes completing their differentiation into Kupffer cells.

The primary function of Kupffer cells is to recycle old red blood cells that no longer are functional. The red blood cell is broken down by phagocytic action and the hemoglobin molecule is split. The globin chains are reutilized while the iron containing portion or heme is further broken down into iron which is reutilized and bilirubin, which is conjugated with glucuronic acid within hepatocytes and secreted into the bile.

Helmy et al. identified a receptor present in Kupffer cells, the complement receptor of the immunoglobulin family (CRIg). Mice without CRIg could not clear complement system-coated pathogens. CRIg is conserved in mice and humans and is a critical component of the innate immune system.