| Abstract: | Concanavalin A (Con A)-induced hepatitis is an experimental hepatitis model in which hepatic injury is caused by the action of cytokines produced by T cells. Using IFN-γ-deficient mice, we previously demonstrated that IFN-γ plays a central role in Con A-induced hepatitis. Here, we show that development of the disease is completely suppressed in gld/gld mice, in which Fas ligand is defective. In contrast, suppression of the disease in lpr/lpr mice was incomplete, since a small amount of the fas mRNA was produced in these mice. The data indicate that activation of the Fas/Fas ligand system is a necessary step in the development of Con A-induced hepatitis. Furthermore, we found that not only fas but also caspase-1 expression was reduced in IFN-γ-deficient mice. Since caspase-1 is an integral component of Fas signal transduction, these observations suggest that IFN-γ-induced activation of both fas and caspase-1 expression causes enhancement of hepatocyte apoptosis resulting in the development of hepatitis. |
