In class today we talked about three kinds of APCs (Antigen Presenting Cells): Dendritic Cells, B Cells, and Macrophages. In the following article researchers in Berlin, Germany found that the ito cells of the liver, also known as the hepatic stellate cells, have the same attributes as APC cells.
Normally ito cells, which account for anywhere from 5%-8% of liver cells, are calm and store vitamin A in the liver. However when activated, say by a period of alcohol abuse or another chemical toxin or a bout of hepatitis, the ito cells release collagen. As a result the normal liver tissue is replaced by fibrous scarring and can result in liver fibrosis and cirrhosis.
According to the article ito cells have another function too. "Upon bacterial infection, Ito cells elicited antigen-specific T cells and mediated protection." The researchers purified and isolated the ito cells. They then added a specific killer T cell antigen to them. The ito cells then presented the antigen to and activated the killer T cells. They behaved just as any other Antigen presenting cell would.
http://www.ncbi.nlm.nih.gov/pubmed/17239632?dopt=Abstract&holding=npg
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Interesting paper. As an editorial says, "This paper raises the following question: what are the roles and importance of diverse antigen-presenting cells in different organs?" And are these cells really macrophages or dendritic cells, trapped to function specifically in certain locations? Could an ito cell travel with antigen to a draining lymph node?
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