Mouse liver-specific CD8(+) T-cells encounter their cognate antigen and acquire capacity to destroy target hepatocytes.

CD8(+) T-cell immune response to liver antigens is often functionally diminished or absent. This may occur via deletion of these autoaggressive T-cells, through the acquisition of an anergic phenotype, or via active suppression mediated by other cell populations. We generated a double transgenic model in which mice express CD8(+) T-cells specific for the lymphocytic choriomeningitis virus nucleoprotein (LCMV-NP) and LCMV-NP as a hepatic neo-autoantigen, to study the immunological response of potentially liver antigen autoaggressive CD8(+) T-cells. Autoreactive transgenic CD8(+) T-cells were analyzed for functionality and cytotoxic effector status. Despite severe peripheral deletion of liver-specific CD8(+) T-cells, a fraction of autoreactive NP-specific CD8(+) T-cells accumulate in liver, resulting in hepatocyte injury and production of auto-antibodies in both male and female mice. NP-specific intrahepatic T-cells showed capacity to proliferate, produce cytokines and up-regulate activation markers. These data provide in vivo evidence that autoreactive CD8(+) T-cells are activated in the liver and developed an inflammatory process, but require additional factors to cause severe autoimmune destruction of hepatocytes. Our new model will provide a valuable tool for further exploration of the immunological response involved in inflammatory liver diseases, including autoimmune hepatitis.

HLA class II influences humoral autoimmunity in patients with type 2 autoimmune hepatitis.

BACKGROUND/AIMS: Type 2 autoimmune hepatitis (AIH) is characterized by the presence of anti-liver kidney microsome (anti-LKM-1) and/or anti-liver cytosol type 1 (anti-LC1) autoantibodies. However, the correlation between these autoantibodies and the genetic background has not been studied. METHODS: Frequencies of HLA class II alleles were compared between the 60 Caucasian children with type 2 AIH and 313 control subjects. The anti-LKM1 antibody reactivity directed against antigenic sites of CYP2D6 was analysed by ELISA. RESULTS: HLA-DQB1 *0201 allele was found to be the primary genetic determinant of susceptibility to type 2 AIH by conferring the highest odd-ratio (OR = 6.4). HLA-DRB1 *03 allele was significantly increased (P < 0.0001) among patients with both anti-LKM1 and anti-LC1 autoantibodies as well as in those with only anti-LC1(+) compared to those with anti-LKM1(+) alone. In contrast, HLA-DRB1 *07 allele was significantly associated (P < 0.0001) with anti-LKM1(+) alone compared to groups with both anti-LKM and anti-LC1 or with LC1+ alone. Children with the DRB1 *07 allele develop anti-LKM1 autoantibodies having a more restricted specificity (2 epitopes) than to those having HLA-DRB1 *03 allele (5 epitopes). CONCLUSIONS: The HLA-DR locus is involved in autoantibody expression, while the DQ locus appears to be a critical determinant for the development of type 2 AIH.