A murine model of acute liver injury induced by human monoclonal autoantibody.

We have previously reported an immunoglobulin (Ig) M autoantibody to hepatocyte-related 190-kd molecules in patients with type 1 autoimmune hepatitis (AIH). This molecule was first isolated by hepatocyte-specific human monoclonal antibody (MoAb). To elucidate the role of this IgM autoantibody in hepatocyte injury, we examined the reactivity of this MoAb to murine hepatocytes and then questioned whether acute hepatic injury could be induced in mice via injection of this MoAb. The reactivity of MoAb was examined via both FACS analysis using murine hepatocytes and immunostaining of liver tissues. We then identified the murine hepatocyte membrane molecule recognized by this MoAb. The role of this MoAb in the immunopathogenesis of AIH was assessed by testing whether its injection into mice could increase serum aminotransferase levels as well as cause changes in liver histology. The present results demonstrate that this MoAb cross-reacted with murine hepatocytes and recognized a 190-kd molecule on the murine hepatocyte membrane just as in human hepatocytes. One hour after the injection of MoAb, the deposition of both IgM and complement component 3 was found in liver tissues. At 8 hours after the injection, serum aminotransferase levels were significantly increased in MoAb-injected mice compared with controls. Histological study revealed massive hepatocyte necrosis in MoAb-injected mice. In conclusion, human MoAb recognized a 190-kd molecule of both human and murine hepatocytes, and the injection of this MoAb to mice resulted in acute liver injury, indicating that this type of autoantibody may play an important role in the immunopathogenesis of AIH.

A novel IgM class autoantibody to a hepatocyte-related 190 kDa molecule in patients with type 1 autoimmune hepatitis.

It has been reported that autoantibodies to hepatocytes are frequently found in patients with autoimmune hepatitis (AIH). To elucidate the nature of these hepatocyte-specific autoantibodies, we attempted to generate a hepatocyte-specific monoclonal antibody (MoAb) from Epstein-Barr virus-transformed peripheral blood mononuclear cells obtained from a patient with AIH. We established a single clone, 2E3, that continued to produce an immunoglobulin M (IgM) antibody (lambda-type). This MoAb had the following properties: it reacted mainly with hepatocyte-derived cell lines, rather than with other cell lines, and it reacted with liver tissue but not with other tissues. By immunoblot analysis, we found that this MoAb recognized a 190 kDa molecule on hepatocytes. The MoAb was able to kill hepatocyte-derived cell lines in the presence of fresh human serum. This cytotoxic effect was completely abrogated by heat inactivation of human serum prior to its addition to cell lines. In addition, an IgM autoantibody that recognized a 190 kDa molecule was also found in patients with AIH but not in those with chronic hepatitis C; its titer correlated significantly with serum alanine aminotransferase (ALT) levels in patients with AIH. In conclusion, we generated a human MoAb that recognizes a 190 kDa molecule on hepatocytes. Because of its ability to mediate complement-dependent cytotoxicity and the presence of similar IgM autoantibody in patients with AIH, we hypothesize this autoantibody may play a role in the immunopathogenesis of AIH.

Clinicopathologic features of patients with hepatocellular carcinoma seropositive for alpha-fetoprotein-L3 and seronegative for des-gamma-carboxy prothrombin in comparison with those seropositive for des-gamma-carboxy prothrombin alone.

BACKGROUND: There has been no study of the clinicopathologic features of patients with hepatocellular carcinoma (HCC) who are seropositive for lectin-reactive alpha-fetoprotein (AFP-L3) alone, or seropositive for AFP-L3 and seronegative for des-gamma-carboxy prothrombin (DCP) in comparison with those who are seropositive for DCP alone. Thus, the present comparative study was performed. METHODS: The clinicopathologic features of HCC patients with either one or two tumors who underwent a hepatectomy (n = 88) were compared among the following five groups according to the seropositivity of AFP, AFP-L3 and DCP: (i) group A, seropositive for AFP above 100 ng/mL, AFP-L3 above 15% and DCP above 100 mAU/mL; (ii) group B, seropositive for AFP-L3 and seronegative for DCP below 40 mAU/mL; (iii) group C, seronegative for AFP below 20 ng/mL, AFP-L3 below 15% and seropositive for DCP; (iv) group D, seropositive for AFP and seronegative for AFP-L3 and DCP; and (v) group E, seronegative for AFP, AFP-L3 and DCP. RESULTS: Group B patients showed a higher incidence of infiltrative-type HCC with an irregular margin (P < 0.05) and a higher frequency of poorly differentiated HCC (P < 0.01) compared with group C patients. Group A patients had larger tumors and more massive-type tumors than group B patients. Our HCC cases showed that advanced clinicopathologic features were demonstrated in the order of group B, group C and group D. Group A and B patients and group D and E patients showed similar characteristics. CONCLUSIONS: Hepatocellular carcinoma patients who were seropositive for AFP-L3 and seronegative for DCP demonstrated clinicopathologic features of more advanced HCC compared with those who were seropositive for DCP alone.