One defining serologic characteristic of PBC is the development of high titer AMA specific for the E2 subunit of PDC-E2 . Mice were bled and screened for the development of AMA. All sera collected at 7 weeks from SJL/J mice immunized with PDC-E2 (group A) showed positive reactivity against PDC-E2 by immunoblot (Fig. 1, lanes 1 and 2) . In contrast, sera isolated at 7 weeks from mice immunized with a-casein (group C) failed to react with PDC-E2 (Fig. 1, lane 3) . All responses from mice immunized with PDC-E2 (group A) were similar to responses of mice immunized with PDC-E2 plus IFN-g (group B), including reactivity with the conserved inner lipoyl domain of PDC-E2 (data not shown). At subsequent time points, through sacrifice (30 weeks), sera reactivity was very much similar to that determined at 7 weeks post-immunization ( Fig. 1, lanes 4 and 5). In contrast, sera isolated at 30 weeks from mice immunized with a-casein (group C) failed to react with PDC-E2 (Fig. 1, lane 6) . Results performed by immunoblot were similar to those obtained by ELISA. Further, sera from mice primed with PDC-E2 (Groups A and B) displayed a typical speckled (punctate) antimitochondrial staining pattern (Fig. 2a) . However, a single mouse primed with PDC-E2 and who received IFN-g (group B) demonstrated an anti-nuclear antibody pattern at a 1:40 dilution. Sera isolated from mice immunized with a-casein (groups C and D) also displayed weak antinuclear antibody staining patterns (Fig. 2b) .