2016 Comprehensive Update of the Banff Working Group on Liver Allograft Pathology: Introduction of Antibody-Mediated Rejection.

The Banff Working Group on Liver Allograft Pathology reviewed and discussed literature evidence regarding antibody-mediated liver allograft rejection at the 11th (Paris, France, June 5-10, 2011), 12th (Comandatuba, Brazil, August 19-23, 2013), and 13th (Vancouver, British Columbia, Canada, October 5-10, 2015) meetings of the Banff Conference on Allograft Pathology. Discussion continued online. The primary goal was to introduce guidelines and consensus criteria for the diagnosis of liver allograft antibody-mediated rejection and provide a comprehensive update of all Banff Schema recommendations. Included are new recommendations for complement component 4d tissue staining and interpretation, staging liver allograft fibrosis, and findings related to immunosuppression minimization. In an effort to create a single reference document, previous unchanged criteria are also included.

Histopathological features of hepatitis C in renal transplant candidates [see comment].

BACKGROUND: Although hepatitis C virus (HCV) infection is common in renal transplant candidates, its clinical significance remains unclear in this population. Little detailed information is available about the histological severity of HCV infection in these patients. We evaluated the liver biopsy features of chronic HCV in a large population of renal transplant candidates and investigated associations between histopathological changes and host- and virus-related factors. METHODS: Thirty-seven patients seropositive for anti-HCV with chronic renal failure (CRF) referred to UCLA Medical Center for kidney or kidney/liver transplantation during the period 1992-1997 were included. HCV genotype and viral load were measured. A multivariate analysis by logistic regression model was performed: age, gender, race, HCV load and genotype, CRF level, aspartate and alanine aminotransferase activity, duration of HCV infection, underlying nephropathy, and alcohol abuse were independent variables; liver histology score was assumed a dependent variable. RESULTS: Liver disease was present in all HCV-infected patients. Logistic regression analysis revealed that histological damage was (P = 0.0017) independently associated with the CRF level; the severity of liver disease, as shown by univariate analysis, being significantly higher in CRF patients not requiring dialysis than among dialysis population. All patients on dialysis showed mild or moderate necroinflammatory activity; the majority (22/28 = 79%) of these individuals had fibrosis, three (3/28 = 11%) dialysis patients had established cirrhosis. Thirty-one (84%) of 37 patients were tested by polymerase chain reaction, 25 (81%) patients had detectable HCV RNA in serum, the mean HCV load among viremic patients was 10.9x10(5) copies/ ml. The most frequent HCV genotypes were la (8/24 = 33%) and 1b (7/24 = 29%), followed by genotype 2b (3/24 = 12%). CONCLUSIONS: Pathological changes on liver biopsy were observed in all HCV-infected patients awaiting renal transplantation. The severity of histologic damage observed on liver biopsy was less in dialysis than predialysis CRF patients. All dialysis patients had mild or moderate necroinflammatory activity; fibrosis was frequent with 11% of them having cirrhosis. The HCV viral load was rather low; no relationship between liver histology changes and virological features of HCV or aminotransferase activity was apparent. Further studies with repeat liver biopsies after kidney transplantation to observe the evolution of HCV-related liver disease after immunosuppressive therapy are indicated. We suggest including liver biopsy in the evaluation of the HCV-infected renal transplant candidate.

Upregulation of heme oxygenase-1 protects genetically fat Zucker rat livers from ischemia/reperfusion injury.

We examined the effects of upregulation of heme oxygenase-1 (HO-1) in steatotic rat liver models of ex vivo cold ischemia/reperfusion (I/R) injury. In the model of ischemia/isolated perfusion, treatment of genetically obese Zucker rats with the HO-1 inducer cobalt protoporphyrin (CoPP) or with adenoviral HO-1 (Ad-HO-1) significantly improved portal venous blood flow, increased bile production, and decreased hepatocyte injury. Unlike in untreated rats or those pretreated with the HO-1 inhibitor zinc protoporphyrin (ZnPP), upregulation of HO-1 by Western blots correlated with amelioration of histologic features of I/R injury. Adjunctive infusion of ZnPP abrogated the beneficial effects of Ad-HO-1 gene transfer, documenting the direct involvement of HO-1 in protection against I/R injury. Following cold ischemia/isotransplantation, HO-1 overexpression extended animal survival from 40% in untreated controls to about 80% after CoPP or Ad-HO-1 therapy. This effect correlated with preserved hepatic architecture, improved liver function, and depressed infiltration by T cells and macrophages. Hence, CoPP- or gene therapy-induced HO-1 prevented I/R injury in steatotic rat livers. These findings provide the rationale for refined new treatments that should increase the supply of usable donor livers and ultimately improve the overall success of liver transplantation.

Regulated expression of the mouse gamma 2b Ig H chain gene is influenced by polyA site order and strength.

Constructs with alterations in the normal order and spacing of polyadenylation sites of the mouse Ig-gamma 2b heavy chain gene were transfected into J558L cell tumor lines (myelomas) and A20 B cell tumor lines (lymphomas) representative of plasma and memory cells, respectively. When the membrane-specific (mb) polyA site was moved from its 3'-location to a position upstream (5') of the secretory (sec) polyA site, the mb site was used preferentially, even though the sec site was still efficiently transcribed. The relative strength of the mb polyA site seems to preclude efficient use of downstream elements. When two sec polyA sites are put in competition with each other in the same transcript, use of the first site predominates in both cell types, implying that the relative strength and the distance between the sites are important for normal regulation. When the sec polyA site is put upstream of the mb polyA site, in the absence of a competing splicing event, the sec polyA site is used preferentially in the myeloma cell but not the lymphoma cell, implying that its use is a regulated event. We therefore conclude that the B cell-regulated strength of the sec polyA site, as well as its 5'-location, relative to the unregulated, but very strong mb polyA site, are important parameters in the regulated expression of mb and sec mRNA in this system.

Plasma cell-regulated polyadenylation at the Ig gamma 2b secretion-specific poly(A) site.

We found that the sequences downstream of the Ig gamma 2b secretory-specific (sec) poly(A) site play an important role in the preferential production of sec Ig mRNA during plasma B cell development. The Ig gamma 2b mRNA production in a deletion mutant (delta-Kpn) lacking the Ig sec poly(A) site and downstream consensus element (dsc) has been previously shown to default to the use of the downstream membrane-specific (mb) poly(A) site. In this study restoration of the Ig sec poly(A) site and dsc to the delta-Kpn gene causes a significant increase in the use of the sec poly(A) site vs mb poly(A) site in stable transfectants of plasma but not memory B cell tumors, indicating plasma cell-specific recognition of the Ig sec dsc. Restoration of the poly(A) cleavage site alone to delta-Kpn did not restore regulation. Substitution of an SV40 downstream poly(A) element for the Ig dsc in the delta-Kpn gene also does not restore regulation. The data further indicate that although the Ig dsc is clearly very important in the plasma cell-regulated expression, the difference in the processing ratios of the restored vs the intact Ig gamma 2b gene in plasma cells suggests that there are other yet to be defined sequences that may also play a role in the intact gene. Insertion of a 130-nucleotide segment of the gene containing the Ig sec poly(A) site and dsc into a heterologous, guanosyl phosphotransferase gene resulted in plasma cell-regulated polyadenylation of the sec poly(A) site. Neither the mb nor the SV40 early poly(A) sites and their respective dscs, in similar gpt chimeras, were regulated. Therefore the region downstream of the Ig sec poly(A) site plays an essential role in regulating polyadenylation at the sec poly(A) site in plasma cells but not memory cells. A model involving a plasma cell-specific recognition factor for the Ig sec dsc is presented.

Factors influencing DTPA conjugation with antibodies by cyclic DTPA anhydride.

Diethylenetriaminepentaacetic acid (DTPA) was conjugated with a practical concentration (300 micrograms/ml) of antibody to human albumin (Ab) and 1083 17-1A monoclonal colorectal antibody (MAb-17-1A) via an acylation reaction using cyclic DTPA anhydride (cDTPAA). The conjugation reaction was favored as pH increased. Bicarbonate buffer at pH 8.2 was chosen for studies of the effect of the cDTPAA-to-antibody ratio on DTPA conjugation with antibody because of its good buffer capacity at that pH. The reaction of cDTPAA with Ab at molar ratios of 2000, 1000, 500, and 100 in the bicarbonate buffer gave rise to 11, 9, 8, and 2 indium atoms incorporated per Ab with 47%, 55%, 59%, and 77% retention of the binding activity. For the conjugation reaction of MAb-17-1A, 29, 28, 31, 11, 4, and 1 indium atoms were incorporated, with the retention of less than 5%, less than 5%, less than 5%, 12%, 60%, and 93% of binding activity when the molar ratio was 5000, 2000, 1000, 500, 100, and 50.