Immunopathological study on the development of swine serum-induced bile duct lesions in BALB/c and DBA/2 mice

To compare the difference in the development of swine serum (SS)-induced bi le duct lesion (BDL) between high responder BALB/c and low responder DBA/2 mice, the mice of both strains injected with SS twice a week for up to 4 we eks were killed and examined immunopathologically after the 2nd, 4th, 6th a nd 8th SS-injection, respectively. In BALB/c mice, BDL developed rapidly fo llowing the SS-injections, and a slight enlargement of common bile ducts ac companied with infiltration of T helper cells and eosinophils was detected after the 2nd SS-injection. From the 4th injection on, BDL was characterize d by proliferation of mucous glands, hyperplasia and hypertrophy of biliary and glandular epithelial cells, periductal fibrosis, infiltration of eosin ophils, plasma cells and T helper cells, and increase of mast cells, result ing in more apparent enlargement of common bile ducts. Several hypertrophie d biliary and glandular epithelial cells were positive for mouse immunoglob ulins and SS. BDL subsided after cessation of the SS-treatment. On the othe r band, in DBA/2 mice, immune response and inflammatory reaction were very weak, and only slight BDL were detected.