NAKAJIMA Shinya Osaka City University Medical School, Research Associate., 医学部, 助手 (50180287)
OKA Hiroko Osaka City University Medical School, Research Associate., 医学部, 助手 (40169090)
SHIOMI Susumu Osaka City University Medical School, Lecturer., 医学部, 講師 (30170848)
SEKI Shuichi Osaka City University Medical School, Lecturer., 医学部, 講師 (50145778)
KUROKI Tetsuo Osaka City University Medical School, Lecturer., 医学部, 講師 (30047328)
|Budget Amount *help
¥2,100,000 (Direct Cost : ¥2,100,000)
Fiscal Year 1990 : ¥1,100,000 (Direct Cost : ¥1,100,000)
Fiscal Year 1989 : ¥1,000,000 (Direct Cost : ¥1,000,000)
Intrahepatic cholestasis is frequently observed in drug-induced allergic hepatitis, even when liver cells are not remarkably injured. But little is known of the exact mechanisms causing the intrahepatic cholestasis in the disease. To study the immunopathogenesis of intrahepatic cholestasis, peripheral blood lymphocytes obtained from the patients were stimulated in vitro with a specific antigen. When the culture supernatants were injected into the mesenteric vein of normal rats, marked decrease in bile flow and the excretion of bile acid was demonstrated in many cases. Thus the sensitized lymphocytes produced a kind of lymphokin, a bile flow-decreasing factor, which we designated "cholestatic factor." For further investigation of this newly detected lymphokine, we conducted experimental studies on its functional mechanism both in vivo and in vitro. The main results obtained were following :
1. Tuberculin-sensitized guinea pigs were intravenously injected with heat-killed Propionibacteriu
m acnes followed by an intravenous injection of purified protein derivatives 7 day later, resulting in the induction of intrahepatic cholestasis. Using this experimental model, the following results were obtained. 1) Both uptake and release of bile acid were inhibited in the hepatocytes prepared from the guinea pigs with cholestasis. 2) The results of the erythritol clearance method indicated that the decrease in bile flow observed in the cholestatic guinea pigs was mostly attributable to the reduced bile excretion from canaliculi. 3) The decrease in the bile acid-independent bile flow was caused by the decrease in bile flow observed in the guinea pigs with cholestasis. 4) There was no change in the permeability of the intrahepatocellular tight junction of the hepatocytes of the cholestatic guinea pigs.
2. T-cell clone producing the cholestatic factor was established in order to study the characteristics of the cells which produce the cholestatic factor. 1) Five T-cell clones which produce the cholestatic factor were established from PPD-stimulated human peripheral blood mononuclear cells. 2) All of the established T cell clones were shown to be CD2^+, CD3^+, CD4^+, CD8^- and CD25^+ by flow cytometrical analysis. 3) These cloned T cells produced the cholestatic factor, IL-2 and IFNgamma, but not IL-4 or IL-4 or IL-6 when stimulated with PPD. 4) The reduction in bile flow was not induced, which a considerably large amount of IL-1, IL-2, IL-4, IL-6, TNF, or IFNgamma were injected into the mesenteric vein of rats. These results suggested that the cholestatic factor may be a novel lymphokine different from the known cytokines.
3. When ursodeoxycholic acid was injected into the mesenteric vein of rats with the cholestatic factor, the decrease in the excretion of bile flow and bile acid was significantly suppressed. Remarkable increase in bile flow was also noted, when ursodeoxycholic acid was administered to normal rats. These results suggested that ursodeoxycholic acid may be effective in the treatment of intrahepatic cholestasis. Less