To magnify the inflammatory environment in SJL/J mice, we injected exogenous IFN-g but such injections failed to alter the pathology of PBC. The addition of IFN-g did not change the specificity or intensity of histologic or serologic effects. These results are not surprising since the pathology observed herein is antigen non-specific. Hence, this system is different from the disease associated features of IFN-g when NOD mice are injected with exogenous cytokines (Xiang and Zaccone, 1999) . Alternatively, treatment of IFN-g may cause classswitching of antigen specific AMA to IgG1. It is possible that IgG1 is not pathogenic. In fact, recently our lab has demonstrated that IgA may significantly contribute to the pathology of PBC (Reynoso-Paz et al., 2000) . In this respect, we should note that mice do not have IgA receptors on their bile duct cells and, in fact, have a significantly different mucosal immune system than that of humans .