A method to assess the distribution and frequency of plasma cells and plasma cell precursors in autoimmune hepatitis

Chronic inflammation exhibiting interface hepatitis and plasma cells in hematoxylin-eosin (H&E)-stained sections is typical of autoimmune hepatitis (AIH), a non-resolving inflammatory liver disease of unidentified cause. Some biopsies may only reveal lymphocytes and occasional granulocytes but no plasma cells. Recent studies on liver biopsies showed that the antibody against multiple myeloma oncogene-1 (MUM1) stained plasma cells (PC), and plasma cell precursors (PCP). Here, liver biopsies from 86 patients were stained with H&E, as well as for MUM1. The portal triad with the highest degree of chronic inflammation (hot-spot PTCI) was chosen for assessing both the topographic distribution and the frequency of MUM1-positive cells. In the 12 untreated AIH cases, MUM1-positive cells were found organized in an irregular ring-like fashion at the peripheral domain of the PTCI, but in none of the three medically-treated AIH cases. Only one out of the remaining 71 liver biopsies exhibited a similar ring-like arrangement, but the PTCI outline was sharp and the number of MUM1-positive cells was low. The highest mean number of MUM1-positive cells at the peripheral domain of the PTCI (59.2 cells) was found in AIH cases (AIH vs. other liver ailments, p<0.05). The highest mean number of MUM1-labelled cells in the core of the PTCI (83.3 cells) was found in PBC cases (PBC vs. other liver ailments p<0.05). Anti-MUM1 permits assessment of qualitative and quantitative PC/PCP changes evolving in autoimmune liver diseases. It is suggested that MUM1 may be of help in the histological differential diagnosis between autoimmune liver diseases and other liver ailments.