1995; Sakai et al. hepatitis not by competitively inhibiting the binding of Jo2 to Fas on hepatocytes, and that a distinct molecule other than Fas may possibly be involved in the protective effect of HFE7A against Jo2-induced hepatic injury. mice reduced the autoimmune symptoms, including those of lymphadenopathy, nephrotisis, arthritis and vasculitis (Nishimura-Morita et al. 1997). Intra-articular administration of RK-8 to human T cell leukemia virus type I (HTLV-I) tax transgenic L-Lactic acid mice, which spontaneously develop arthritis and are considered to be one of the most suitable models for human rheumatoid arthritis (RA), was effective in improving paw swelling in these mice (Fujisawa et al. 1996). Fas expression was also detected on fibroblast-like synoviocytes. It was reported that anti-human Fas antibody CH-11 induces apoptosis in synoviocytes and infiltrating mononuclear cells from RA patients in vitro or in an in vivo RA model in which human RA tissue is grafted onto severe combined immunodeficient (SCID) mice (Nakajima et al. 1995; Firestein et al. 1995; Sakai et al. L-Lactic acid 1998). These facts suggest that anti-Fas antibody would be a candidate as a therapeutic agent for autoimmune diseases. On CACNLB3 the other hand, administration of Jo2, another hamster anti-mouse Fas antibody, is lethal when administered to mice either intravenously (i.v.) or intraperitoneally (i.p.) (Ogasawara et al. 1993). Administration of Jo2 caused fulminant hepatitis or hemorrhage and death in mice, and Jo2-induced lethality is associated with intensive hepatocyte death and marked elevation of serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT; Ogasawara et al. 1993). Injection of a caspase inhibitor protects mice against Jo2-induced apoptosis of hepatocytes and lethality (Rodriguez et al. 1996). These observations suggest that hepatocytes are the primary target and that Jo2-induced death of hepatocytes is the cause of lethality. We have obtained the unique mouse anti-Fas mAb HFE7A, which reacts with both human and mouse Fas (Ichikawa et al. 2000; Yoshida-Kato et al. 2000). Although administration of HFE7A induced apoptosis in thymocytes, it did not show any signs of hepatotoxicity in mice (Ichikawa et al. 2000). HFE7A showed a therapeutic effect against lymphadenopathy that had developed in MRLmice and also induced apoptosis in synovial cells from RA patients in vitro (Ichikawa et al. 2000). L-Lactic acid Interestingly, HFE7A rescued mice from Jo2-induced lethal fulminant hepatitis (Ichikawa et al. 2000). In this study, we investigated the mechanism of the protective effect of HFE7A against Jo2-induced hepatitis and we discovered the possibility that HFE7A may exert a protective effect against Jo2-induced hepatitis by inhibiting apoptosis in hepatocytes without competitively inhibiting the binding of Jo2 to Fas on hepatocytes. Materials and methods Animals and antibodies HFE7A, mouse anti-human/mouse Fas mAb was obtained as mentioned previously (Ichikawa et al. 2000; Yoshida-kato et al. 2000). BALB/c mice were purchased from Charles River Japan (Yokohama, Japan). Fas knockout mice were kindly provided by Dr. Yonehara at Kyoto University. All the mice were maintained and used in accordance with the guidelines for the care and use of experimental animals of Daiichi Sankyo Co., Ltd. All experiments were approved by the Animal Experimentation Ethics Committee of Daiichi Sankyo Co., Ltd. Induction of Jo2-hepatitis BALB/c mice were i.v. injected with 6.7?g of Jo2, hamster anti-mouse Fas mAb (BD Bioscience, Franklin Lakes, NJ, USA). At 0, 10, 30 or 60?min after the Jo2 injection, 67?g of HFE7A was additionally i.v. injected. The survival ratio of each group was observed until 24?h after the Jo2 injection. AST and ALT level in Jo2-treated mice Twelve-week-old BALB/c female mice L-Lactic acid were i.v. injected with 6.7?g of Jo2. At 0, 10 or 60?min after the L-Lactic acid Jo2 injection, 67?g of HFE7A was additionally.
