A role of mast cells for hepatic fibrosis in primary sclerosing cholangitis.

We encountered four patients with overt primary sclerosing cholangitis (PSC) which were histologically classified into stage 2 or 3. We examined the expression of stem cell factor (SCF), a ligand of c-kit, in injured bile ducts by immunohistochemistry, and mast cells were identified by immunohistochemistry using anti-HMCT (human mast cell tryptase) and anti-c-kit antibodies to clarify their relation with portal fibrosis coincident with destroyed bile ducts. SCF was detected in the epithelia of most bile ducts in PSC, and many HMCT- and c-kit-positive mast cells were found in portal tracts. Image analysis showed more significant numbers of c-kit-positive mast cells per area of portal tract in PSC than in chronic hepatitis C, and they might increase from stage 2 to 3. c-Kit-positive cells infiltrated into the portal tracts with SCF-positive destroyed bile ducts, and c-kit mast cells should be investigated in detail to make a role for portal fibrosis in PSC.