Researchers at the Karolinska Institutet have published detailed descriptions of the immune cells residing in the human bile duct in Science Translational Medicine. The human biliary tract had remained one of few unexplored immunological niches because of difficulties in accessing this site.
"Difficulties in studying this organ has hampered our understanding of biliary diseases, many of which are severe with dismal prognosis," says Niklas Björkström, who led the study.
To overcome this, the team employed a novel clinical examination method for retrieving and studying immune cells localized in the biliary system. With this method, they managed to retrieve immune cells from the bile duct of 125 patients and in detail characterize each of these immune cells.
The researchers compared immune cells from patients with primary sclerosing cholangitis (PSC), a severe inflammatory disease of the biliary system, with immune cells from non-inflammatory controls. PSC patients had a high infiltration of neutrophils and T cells in their bile ducts that seemed to cooperate in causing an inflammatory environment.
"Our study sheds new light on the immunological processes involved in PSC," adds Björkström. "It also helps uncover the immunological niche of human bile ducts, which is a major step forward and will provide an important resource for future studies of the immune response in biliary disorders."