PRIMARY BILIARY-CIRRHOSIS (PBC) - ANTIGEN-PRESENTING CELLS DIFFER IN THEIR DISTRIBUTION IN EARLY AND LATE-STAGE PBC AND INVOLVE THE DUCTAL,BUT NOT THE DUCTULAR COMPARTMENT

We have studied the distribution patterns of antigen-presenting cells (APCs) in different stages of primary biliary cirrhosis (PBC). 58% of cases with early PBC (stages I and II) exhibited dendritic APCs (S-100 (+), HLA-DR(+), KiMlp(+)) in bile duct epithelia. In contrast, APCs, w ere not detected in ductular proliferations occurring in late PBC (sta ges III and IV), but occurred in portal tracts and piecemeal necroses. There was a correlation between the presence of APCs and HLA-DR expre ssion in bile ducts but, in contrast to former studies, we noted a het erogeneous ductal HLA expression. These observations support the hypot hesis that: 1) APC distribution in PBC may change as a function of sta ge, involving hepatic parenchyma in late PBC; 2) ductular epithelia ma y not represent a target for immune attack, because APCs do not accumu late in these structures; and 3) HLA expression in bile ducts may be h eterogeneous, suggesting one mechanism why bile duct destruction in PB C does not take place in a synchronous way.