1B). Liver-infiltrating T cells and splenocytes isolated from males and 4-week-old or 14-week-old Cisplatin mouse females showed low specific cytotoxicity against type 2 AIH antigens compared with 7-week-old female mice (Fig. 1C). Seven-week-old female C57BL/6 mice were susceptible, whereas 4-week-old and 14-week-old females were less prone to the development of an experimental AIH. Seven-week-old female mice were also more vulnerable than males at the same age. In this animal model, as was observed in humans, female sex and age are susceptibility factors for the onset of AIH. Antibodies against the injected xenoantigens were measured in the four groups

of mice. Females vaccinated at 7 weeks of age showed the highest titer of antibodies (P < 0.05) (Fig. 2A). Titers reached their maximal

level in the first month and remained elevated until the 8th month post-vaccination. When autoantibodies against murine formiminotransferase-cyclodeaminase (FTCD) and CYP2D9 (the murine homolog of human CYP2D6) were measured, female mice vaccinated at 7 weeks of age showed significantly higher levels of anti-mFTCD autoantibodies than mice from other groups (Fig. 2C). No PF-01367338 molecular weight statistically significant differences in reactivity against CYP2D9 were found between sera from all four groups (Fig. 2B). However, autoantibodies level increased over time, a feature evident in 7-week-old female mice sera reactivity against mFTCD. Interestingly, levels of mFTCD autoantibodies correlated with the histological activity index in mice from all four groups, suggesting a possible role for B cell

response against mFTCD in development of the disease (Fig. 2D). To characterize this B cell response, reactivity against xenoantigens (CYP2D6 selleck screening library and FTCD) and mFTCD were compared by western blot to detect high-affinity antibodies targeting linear epitopes. Early on, reactivity against injected antigens was found in all mice (human CYP2D6-FTCD) (Fig. 2E). However, a shift of B-cell reactivity (human FTCD) to autoreactivity (murine FTCD) occurred in female mice (Fig. 2E). This type of B cell shift to autoreactivity was not observed in male mice. The expression level in the liver of the targeted antigens, mFTCD and CYP2D9 could potentially influence the reactivity of specific T cells and development of AIH. Therefore, their expression level was assessed in livers from newborn and 7-week-old C57BL/6 mice. Male and female newborn (data not shown) and 7-week-old C57BL/6 mice showed similar hepatic expression levels of both mFTCD and CYP2D9 (Fig. 3A). Therefore, the amount of autoantigen in hepatocytes is not related to the female’s susceptibility to AIH. The thymic expression level of FTCD and CYP2D9 was measured in C57BL/6 newborn mice. No differences were observed between males and females (Fig. 3B). FTCD thymic expression level was lower than that of CYP2D9 (Fig.