Morphology And Expression Of CD₆₈,TGFβ₁,α-SMA In Benign Biliary Stricture

OBJECTIVE To explore the morphologic character and mechanism of the benign biliary stricture. METHODS 14 cases of biliary scars of patients with the benign biliary stricture and 10 cases of normal biliary tissues were collected. The microstructure and ultrastructure of tissues in both groups were studied with light microscopy under HE, Masson, Von Gison's staining and Scanning electron microscopy and Transmission electron microscopy respective. Intensity of expression and location of CD₆₈, TGF β₁, α-SMA were studied with immunohistochemical SP staining. RESULTS Light microscopy showed that collageous fiber was arranged in a dense and disorderly way in the biliary scars. Scanning electron microscopy showed that mucosa membrance of biliary scars was missing and arranged in a coralliform and collageous fiber was thickened and arranged in a disorderly way. Infiltration of white cell in the biliary scars was found. Transmission electron microscopy showed that myofibroblast was existed and extracellular matrix was overdisposited in the biliary scars. Immunohistochemical test showed the high expression of CD₆₈,. TGFβ₁,. α -SMA in the biliary scars. CD₆₈ was mainly found in macrophage, a small amount in fibroblast, neutrophil, lymphocyte; Mean positive cells in the biliary scars were 29.64 ± 7.65, which were significantly different from that in normal bile duct. α -SMA was mainly found in myofibroblast, smooth muscle of blood vessel and bile duct, inflammatory cell such as neutrophil, lymphocyte; Mean positive cells in the biliary scars were 65.36 ± 19.08, which were significantly different from that in normal bile duct. In the biliary scars numbers of neogenetic vessel increased , the partial walls of which were significantly thickened. Mean numbers of thickening one were 10. 71±4. 38, which were significantly different from that in normal bileduct. TGF P i was mainly found in granulation tissues, fibroblasts, endothelial cells of blood vessel and massive inflammatory cells such as neutrophil, lymphocyte. Mean positive cells in the biliary scars were 40.86+13. 55, which were significantly different from that in normal bile duct. CONCLUSIONS The morphologic character of the benign biliary stricture include the lasting existence of chronic inflammation, poorly local blood supply, overdisposition of collageous fiber, existence of MFB. Elonged infiltration of macrophage in bile duct wall is a major cause of formation of the benign biliary stricture. Macrophage can promote the transformation of myofibroblast and overdisposition of collageous fiber through excretion of TGFP , with a paracrine mechanism. Myofibroblast is a main factor resulted in contraction of biliary scars. Ischemia and anoxia in biliary scars may be a cause of formation of the biliary scars. The role of gall, retroflux of intestinal fluid and foreign-body reaction resulted from suture with silk thread during reconstruction of traumatic bile duct are probably crucial factors resulted in lasted infiltration of macrophage in bile duct wall, which strengthen formation of the benign biliary stricture.