Mast cell distribution and activation in chronic pancreatitis

Chronic pancreatitis (CP) is characterized by mononuclear inflammatory cell infiltration and replacement of the destroyed parenchyma by fibrous tissue . Recently, mast cells have been implicated in chronic inflammatory process es with fibrous tissue deposition. Therefore, the number and distribution o f mast cells and their state of activation were evaluated in 12 normal spec imens and in 46 specimens of CP with different causes (alcoholic, tropical, and idiopathic). Furthermore, the presence of stem cell factor (SCF), the main mast cell growth factor, and of its receptor, c-kit, was also assessed . In CP tissues, mast cells were localized both in the fibrotic areas and i n the residual acinar parenchyma. The total number of mast cells was signif icantly higher in CP than in the normal pancreas (P <.0001) and correlated positively with the extent of fibrosis and the intensity of inflammation. I mmunoglobulin E (IgE)-dependent mast cell activation was higher in CP than in the normal pancreas. No differences in mast cell number or IgE positivit y were found among the 3 causes of CP. SCF- and c-kit-immunoreactive mast c ells were mostly localized in fibrous tissue and around regenerating ducts, which were also positive for c-kit but were negative for SCF. These result s suggest that mast cells, activated by an IgE-dependent mechanism and/or b y an SCF-c-kit autocrine loop, are a relevant component of the inflammatory infiltrate in CP, independent of the underlying cause. Their localization near degenerating acini and regenerating ducts might indicate that they pla y a crucial role in tissue destruction and remodeling in CP. Hum PATHOL 32: 1174-1183. Copyright (C) 2001 by W.B. Saunders Company.