Cells In Primary Biliary Cirrhosis Research Articles

Autoreactive liver-infiltrating T cells in primary biliary cirrhosis recognize inner mitochondrial epitopes and the pyruvate dehydrogenase complex

Primary biliary cirrhosis (PBC) is characterized by lymphoid infiltrates in the portal tracts of the liver and the occurrence of antimitochondrial autoantibodies in serum directed against components of the pyruvate dehydrogenase complex and the other alpha-keto acid dehydrogenase complexes. These enzymes are located on the inner mitochondrial membrane. The destruction of the biliary tract in PBC is thought to be mediated by autoreactive liver-infiltrating T cells exerting cytotoxic activity or releasing certain lymphokines. In this study the reactivity of liver infiltrating T cells was shown to a bovine pyruvate dehydrogenase complex (PDH), a purified E2 subunit (PDH-E2) and a crude preparation of human liver mitoplasts (HLM), i.e. mitochondria depleted of their outer membranes. Peripheral blood lymphocytes (PBL) from 11 of 15 patients (73.3%) with PBC showed a HLA class II-restricted proliferative response to the PDH complex whereas PBL from patients with chronic viral hepatitis, autoimmune hepatitis or extrahepatic cholestatic icterus (n = 20) and healthy controls (n = 5) did not. In addition 13 of 15 PBL from patients with PBC (86.6%) and three of nine PBL from patients with autoimmune hepatitis (33.3%) reacted with the crude HLM preparation whereas no reactivity was found with PBL from eight patients with chronic viral hepatitis, three patients with extrahepatic cholestasis or five healthy controls. Clonal analysis of 115 liver-infiltrating T cells derived from two diagnostic liver biopsies of patients with PBC revealed a predominance of activated CD4+CD8- T helper cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Membrane dihydrolipoamide acetyltransferase (E2) on human biliary epithelial cells in primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is associated with serum antibodies that react with the dihydrolipoamide acetyltransferase component (E2) of the mitochondrial pyruvate dehydrogenase complex. We have sought the presence of E2 on the surface of human intrahepatic biliary epithelial cells (BEC). Cultured BECs from PBC but not normal liver were found to have E2 on the membrane after three days' culture. Isolated, viable cells examined by laser-scanning confocal microscopy revealed the pattern of E2 staining on the membrane to be similar to that seen with the membrane glycoprotein marker, HEA-125. By contrast, BECs from normal liver showed membrane staining only with HEA-125. When BECs were fixed before incubation with antibody to E2, cytoplasmic staining was observed. Our results suggest that E2 is present on the surface of biliary epithelial cells in PBC, and support the idea of a pathogenetic association between antimitochondrial antibodies and bileduct damage.

Blood and liver-infiltrating lymphocytes in primary biliary cirrhosis: Increase in activated T and natural killer cells and recruitment of primed memory T cells

We used two-color and three-color flow cytometric analysis to study phenotypical activation and functional subsets of T and natural killer cells in the blood and liver tissue of patients with primary biliary cirrhosis, other chronic liver diseases and the blood of healthy subjects. The changes in blood lymphocyte phenotype in patients with primary biliary cirrhosis and other chronic liver diseases were similar and comprised elevated relative or absolute numbers of activated human leukocyte antigen-DR + T subset (CD4+ and CD8+) cells and DR+ natural killer-like (CD16+) cells. B cell (CD19+) numbers were normal. In primary biliary cirrhosis a selective reduction in T cells of suppressor-inducer (CD45RA + CD4 + ) type was registered. The human leukocyte antigen-DR expression among CD4+ T cell subsets was investigated further in primary biliary cirrhosis and healthy controls using triple antibody flow cytometric analysis. Phenotypical cell activation was confined to helper T cells of the primed, memory (CD45RO + CD4+) type. The decrease in suppressor-inducer T cells in primary biliary cirrhosis was paralleled by a reciprocal increase in primed memory T cells. Several significant differences were observed when blood and liver-infiltrating cells from primary biliary cirrhosis patients were compared. In the liver tissue, the CD4/CD8 ratio was decreased, the relative activation of T-subset cells and NK cells was further increased, the suppressor-inducer T subset was further depressed and the primed memory T subset was increased. The cytotoxic T-cell subset (CD11b-) dominated within the CD8+ population. In liver tissue from other chronic liver disease subjects, a lower CD4/CD8 ratio was found compared with primary biliary cirrhosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of HLA-DR antigens on interlobular bile ducts in primary biliary cirrhosis and other hepatobiliary diseases: An immunohistochemical study

Using a monoclonal antibody to α chains of HLA-DR antigens, we found that damaged biliary epithelial cells in primary biliary cirrhosis (PBC) and, to a lesser degree and frequency, in other hepatobiliary diseases expressed HLA-DR antigens, while normal bile ducts did not. There was no correlation between biliary epithelial expression of HLA-DR antigens and intraepithelial migration of HLA-DR-positive cells. In PBC, HLA-DR antigens were strongly expressed on the damaged bile ducts surrounded by no or mild inflammatory cell infiltration (nonflorid duct lesion) and on those surrounded by intense lymphoid cells (florid duct lesion). Immunoelectron microscopy confirmed the presence of HLA-DR antigens on the cellular membranes of damaged biliary epithelial cells. Although expression of HLA-DR antigens on bile ducts may itself be a nonspecific epiphenomenon of damaged bile ducts, it seems possible in PBC that biliary epithelial cells are at first damaged in some way and express HLA-DR antigens (and probably self-antigens), and then fall victim to an autoimmune reaction characterized by marked lymphoid cell infiltration (florid duct lesions). The agent causing nonflorid duct lesions is unknown. The reasons why such expression does not lead to immunologic reactions in other hepatobiliary diseases are only speculative.

Circulating activated B cells in primary biliary cirrhosis.

Since patients with primary biliary cirrhosis (PBC) have evidence of abnormal function of the humoral immune system, we determined if B cells from patients with this disease show evidence of activation and can be stimulated by polyclonal activators. Using a reverse hemolytic plaque assay, it was found that patients with PBC had a significant increase in the number of circulating immunoglobulin-secreting cells, compared to normal controls and patients with chronic type B hepatitis virus (HBV) infection. However, the total number of activated cells was less than 1% of the total circulating B-cell population. Furthermore, we were unable to detect an increase in the expression of transferrin receptors, a membrane receptor associated with B-cell activation, in the majority of B cells in patients with PBC. In other studies, immunoglobulin production by lymphocytes from patients with PBC, when stimulated with the polyclonal activators pokeweed mitogen and Epstein-Barr virus (EBV), was reduced. This hyporesponsiveness was not due to a decrease in the number of B cells, as determined by staining with the monoclonal antibody anti-Leu 12. Furthermore, the decreased response to B cells to polyclonal activation in PBC patients was not due increased suppressor T-cell function, since EBV-simulated cultures of lymphocytes from patients with PBC demonstrated diminished suppression of immunoglobulin-secreting cells after 14 days of culture compared to controls. These findings suggest that the humoral abnormalities in PBC are due to the activation of a small subpopulation of B cells rather than to generalized B-cell hyperactivity.

Quantitation of hepatic granulomas and epithelioid cells in primary biliary cirrhosis.

The number of granulomas and loosely arranged epithelioid cell foci in wedge liver biopsy specimens of 39 patients with primary biliary cirrhosis were counted and correlated with other hepatic lesions. Granulomas and cell foci were present in 76.9 and 87.2% of the patients, respectively; their numbers varied greatly from case to case (mean +/- S.D.: 2.4 +/- 3.4 per cm2 and 4.7 +/- 5.5 per cm2 of liver section; range: 0 to 18.5 per cm2 and 0 to 23.3 per cm2, respectively) and decreased as bile duct loss progressed. There was positive correlation between the number of cell foci with the extent of florid duct lesions, and negative correlation with hepatic fibrosis and deposition of copper granules.

Abnormalities of immunocompetent cells in primary biliary cirrhosis.

Primary biliary cirrhosis (PBC) is a chronic cholestatic progressive liver disease frequently associated with various immunological abnormalities. We have studied the influence of normal and PBC adherent cells (AC) on peripheral blood lymphocytes (PBL) colony growth both in liquid and soft agar culture. Co-culture experiments with different combinations of AC and PBL of PBC patients and normal donors provided evidence that PBC adherent cells function abnormally. However, this impaired function is not the sole factor involved, since the number of colonies formed by PBC lymphocytes in the presence of normal AC was twice the normal value. The possibility that this increase is correlated with the state of activation of T cells is discussed in the light of the high number of DR-positive T cells found in the PBC patients studied. Finally, none of these immunological abnormalities was related to the stage of the disease.

A MORPHOLOGICAL STUDY ON BILE DUCT LESIONS IN PRIMARY BILIARY CIRRHOSIS

Morphological changes of interlobular bile ducts in primary biliary cirrhosis and chronic hepatitis were investigated. Results were as follows : 1) Epithelial cell swelling and/or flattening, karyopyknosis, vacuolated cytoplasm and inflammatory cells in the epithelium were generally observed in primary biliary cirrhosis and chronic hepatitis. Stratification, obstructed lumen or cellular debris and destruction of the wall were more often found in primary biliary cirrhosis than in chronic hepatitis.2) The portal tracts were markedly infiltrated by inflammatory cells in primary biliary cirrhosis and chronic hepatitis. Follicular formation and plasma cell infiltration were usually seen in primary biliary cirrhosis. Granuloma was never found in chronic hepatitis.3) There were same epithelial changes between symptomatic primary biliary cirrhosis and asymptomatic one. Granulomas were more frequently seen in asymptomatic primary biliary cirrhosis than in symptomatic cases.4) Numbers of interlobular bile ducts per portal tracts were 0.23 in symptomatic primary biliary cirrhosis and 1.22 in chronic hepatitis. In 3 asymptomatic primary biliary cirrhosis, those were 0.61, 0.87 and 0.71, respectively.5) The rates of portal tracts without interlobular bile ducts were 81% in symptomatic primary biliary cirrhosis and 18% in chronic hepatitis. In 3 asymptomatic primary biliary cirrhosis, the rates were 72%, 50% and 43%, respectively.6) Serial sections revealed that some bile ducts can be able to followed by ductules in 2 asymptomatic primary biliary cirrhosis.

Reduction in peripheral blood K cells and activated T cells in primary biliary cirrhosis.

Lymphocyte subpopulations were measured in the peripheral blood of 13 patients with primary biliary cirrhosis (PBC), 13 with chronic active hepatitis (CAH), and 16 age- and sex-matched normal subjects. A significant, relative and absolute, reduction in activated T cells and K cells, compared with that in normal subjects, was found in PBC but not in CAH. The reduction in K cells observed in PBC was found to be accompanied by a parallel decrease in lymphocyte-mediated antibody-dependent cytotoxicity.

In vitro cell-mediated cytotoxicity in primary biliary cirrhosis and chronic hepatitis. Dysfunction of spontaneous cell-mediated cytotoxicity in primary biliary cirrhosis.

The in vitro cytotoxic function and target cell specificity of peripheral blood lymphocytes from selected patients with primary biliary cirrhosis and hepatitis B surface antigen-negative chronic hepatitis were investigated using 51Cr-labeled human Chang and EL-4 mouse sarcoma cell targets in assays of spontaneous cell-mediated cytotoxicity (SCMC) and mitogen-induced cellular cytotoxicity (MICC). In addition, antibody-dependent cellular cytotoxicity (ADCC) against Chang cells was assessed. At an effector-to-target cell ration of 100:1, the mean SCMC against Chang cells was much less in patients with primary biliary cirrhosis than that in either the controls (P less than 0.001) or the patients with chronic hepatitis (P less than 0.005) whereas the value for patients with chronic hepatitis did not differ significantly from that of the controls. The mean SCMC against EL-4 mouse sarcoma cells was also less in patients with primary biliary cirrhosis than in controls (P less than 0.005) whereas the value for chronic hepatitis was not significantly different from that of the controls or patients with primary biliary cirrhosis. In contrast, MICC against both targets and ADCC against Chang cells were similar for each group. Comparison of SCMC and MICC against both target cells, measured simultaneously, showed similar cytotoxic potenital against both target cells for each group. Effector cells capable of mediating cytotoxicity in each assay were defined by testing the cytotoxic function of lymphocyte subpopulations isolated from two representative patients with each disease using techniques of immunoabsorbent affinity chromatography and Fc receptor binding to antigen-antibody complexes. In both primary biliary cirrhosis and chronic hepatitis SCMC and ADCC were mediated by a subpopulation of lymphocytes which lack surface immunoglobulin (sIg-) and bear Fc receptors (Fc+). In contrast, MICC was mediated by sIg- cells which lack Fc receptors. Lymphocytes bearing sIg- were not cytotoxic in any assay. These results establish a difference in cytotoxic function in primary biliary cirrhosis and chronic hepatitis by defining the presence of a defect in spontaneous cytotoxic function of sIg-, Fc+ lymphocytes against Chang cells in primary biliary cirrhosis.