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.

Detection of smoothelin expression in the urinary bladder is strongly dependent on pretreatment conditions: a critical analysis with possible consequences for cancer staging.

Distinguishing urinary bladder muscularis propria (MP) from muscularis mucosae (MM) is crucial in bladder cancer staging. Immunohistochemical staining for the smooth muscle-specific protein smoothelin has been reported to be a robust marker for MP. The aim of this study was to investigate how smoothelin immunostaining in the bladder varies with pretreatment techniques and if it can be used to discriminate between MM and MP. Immunohistochemistry (IHC) for smoothelin was performed on nontumoral sections from 18 cystectomy specimens using three different pretreatment protocols. The immunoreactivity of MM, MP and blood vessels was scored semiquantitatively. Staining intensity depended strongly on the different pretreatment protocols used. Heat-induced epitope retrieval (HIER) in alkaline buffer resulted in the strongest staining with a moderate or strong immunostaining of the MP in 18/18 (100%) of cases, but in 11/18 (61%), the MM was moderately or strongly stained. HIER in acidic buffer resulted in a suboptimal staining of the MP. Enzymatic pretreatment resulted in absent or weak staining. In conclusion, smoothelin IHC is strongly dependent on epitope retrieval, and smoothelin staining did not discriminate reliably between MP and MM with any of the tested pretreatment protocols.