Safety of sofosbuvir-based regimens after liver transplantation: longitudinal assessment of renal function in the prospective ANRS CO23 CUPILT study

BACKGROUND

In liver transplant recipients with hepatitis C virus recurrence, there is concern about renal safety of sofosbuvir-based regimens. Changes in serum creatinine or in the estimated glomerular filtration rate (eGFR) under treatment are used to look for possible renal toxicity. However, serum creatinine and eGFR are highly variable.

AIM

To analyse renal function trajectory with numerous assays of serum creatinine over a long period of time.

METHODS

In a multicentre cohort of 139 patients, the eGFR was obtained from serum creatinine using the Chronic Kidney Disease-Epidemiology Collaboration (CKD-EPI) equation. Slopes of eGFR were defined as a change in eGFR during a period divided by time. Pre-treatment, on-treatment and post-treatment periods were 9 months, 3-9 months and 4.5 months. Interactions between eGFR slopes and the pre-treatment eGFR, use of ribavirin or mycophenolate mofetil, and stage of fibrosis were addressed. On-treatment eGFR slopes were separated in tertiles. Pre- and post-treatment eGFR slopes were compared globally and according to tertiles.

RESULTS

The post-treatment eGFR slope was significantly better than pre-treatment eGFR slope (+0.18 (IQR -0.76 to +1.32) vs -0.11 (IQR -1.01 to +0.73) mL/min/1.73 m² /month, P = 0.03) independently of the pre-treatment eGFR (P = 0.99), ribavirin administration (P = 0.26), mycophenolate mofetil administration (P = 0.51) and stage of fibrosis (F3 and F4 vs lower stages, P = 0.18; F4 vs lower stages, P = 0.08; F4 Child-Pugh B and C vs lower stages, P = 0.38). Tertiles of on-treatment eGFR slopes were -1.71 (IQR -2.54 to -1.48), -0.78 (IQR -1.03 to -0.36) and +0.75 (IQR +0.28 to +1.47) mL/min/1.73 m² /month. Pre- and post-treatment eGFR slopes were not significantly different according to tertiles (respectively, P = 0.34, 0.08, 0.73).

CONCLUSION

The eGFR varies during treatment and gives a confusing picture of the renal safety of sofosbuvir-based regimens. In contrast, longitudinal assessment of the eGFR shows a rising trajectory over longer time, meaning that these therapies are safe for the kidneys in our cohort of liver transplant recipients.

Bone status and fractures in 85 adults with Wilson's disease

Wilson's disease is characterized by copper deposition, especially in the liver and central nervous system. We assessed the prevalent fractures and bone mineral density (BMD) and related risk factors in 85 patients. BMD was normal, but patients with severe neurological involvement, low BMI, and/or amenorrhea are at risk for fractures.

INTRODUCTION

Wilson's disease (WD) is characterized by copper deposition, especially in the liver and central nervous system. Two studies showed a high prevalence of osteoporosis in WD patients. We wanted to assess the prevalent fractures and bone mineral density (BMD) and to identify risk factors for bone loss and fractures in a large group of WD patients.

METHODS

In this prospective cross-sectional survey at National center of reference for WD, we included 85 patients, 47 women, and 38 men, with a mean age of 35 ± 10 years, and mean time from diagnosis to study of 21 ± 9 years; 57 (67%) patients had neurological signs. Peripheral fractures, prevalent radiological vertebral fractures (VFx), and dual-energy X-ray absorptiometry BMD measurements at the femoral neck (FN) and lumbar spine (LS) were studied.

RESULTS

Mean LS and FN Z-score was normal (-0.37 ± 1.20 at LS and -0.06 ± 1.20 at FN). BMI <19 kg/m(2) and amenorrhea were associated with low BMD. Prevalent peripheral fractures were noted in 43 (51%) and VF in 7 (8%) patients. Severity of neurological involvement and male sex was associated with peripheral fractures, whereas older age, severe neurological involvement, and low BMD and Z-score values were associated with VF.

CONCLUSION

Our data showing normal BMD overall do not support routine bone status evaluation in adults with WD. However, patients with severe neurological involvement, low BMI, and/or amenorrhea are at risk factors for fractures and may require specific monitoring.

Very prolonged liposomal amphotericin B use leading to a lysosomal storage disease

Amphotericin B is a powerful polyene antifungal drug used for treating systemic fungal infections and is usually administered for a short period. Side effects after prolonged use are unknown in humans. Here we report the case of a 28-year-old man suffering from chronic granulomatous disease (CGD), treated for invasive cerebral aspergillosis with liposomal amphotericin B (L-AmB) for a very long time (8 consecutive years). We describe the efficacy and safety of this treatment in the long term. Aspergillosis was kept under control as long as L-AmB therapy was maintained, but relapsed when the dose was reduced. No overt renal toxicity was noted. The patient gradually developed hepatosplenomegaly and pancytopenia. Abnormalities of bone marrow were similar to the sea-blue histiocyte syndrome. Liver biopsy showed images of nodular regenerative hyperplasia related to CGD as well as a histiocytic storage disease. We discuss the very prolonged use of L-AmB leading to the development of a lysosomal storage disease.

Persistence of yellow fever vaccine-induced antibodies after solid organ transplantation

Immunization using live attenuated vaccines represents a contra-indication after solid organ transplantation (SOT): consequently, transplant candidates planning to travel in countries where yellow fever is endemic should be vaccinated prior to transplantation. The persistence of yellow fever vaccine-induced antibodies after transplantation has not been studied yet. We measured yellow-fever neutralizing antibodies in 53 SOT recipients vaccinated prior to transplantation (including 29 kidney recipients and 18 liver recipients). All but one (98%) had protective titers of antibodies after a median duration of 3 years (min.: 0.8, max.: 21) after transplantation. The median antibody level was 40 U/L (interquartile range: 40-80). For the 46 patients with a known or estimated date of vaccination, yellow-fever antibodies were still detectable after a median time of 13 years (range: 2-32 years) post-immunization. Our data suggest there is long-term persistence of antibodies to yellow fever in SOT recipients who have been vaccinated prior to transplantation.

Fibrosing cholestatic hepatitis in HIV/HCV co-infected transplant patients-usefulness of early markers after liver transplantation

We characterized fibrosing cholestatic hepatitis (FCH) in a large cohort of HIV/HCV co-infected patients. Between 1999 and 2008, 59 HIV infected patients were transplanted for end-stage liver disease due to HCV. Eleven patients (19%) developed FCH within a mean period of 7 months [2-27] after liver transplantation (LT). At Week 1 post-LT, the mean HCV viral load was higher in the FCH group: 6.13 log(10) IU/mL ± 1.30 versus 4.9 log(10) IU/mL ± 1.78 in the non-FCH group, p = 0.05. At the onset of acute hepatitis after LT, activity was moderate to severe in 8/11 HIV+/HCV+ patients with FCH (73%) versus 13/28 (46%) HIV+/HCV+ non-FCH (p = 0.007) patients. A complete virological response to anti-HCV therapy was observed in 2/11 (18%) patients. Survival differed significantly between the two groups (at 3 years, 67% in non-FCH patients versus 15% in FCH patients, p = 0.004). An early diagnosis of FCH may be suggested by the presence of marked disease activity when acute hepatitis is diagnosed and when a high viral load is present. The initiation of anti-HCV therapy should be considered at this point.

[Wilson disease: clinical and biological aspects]

Wilson disease is an autosomal recessive disorder of copper excess. This illness results from mutations of the ATP7B gene (chromosome 13, MIM# 277900). The discovery of the gene allowed a better understanding of cytosolic copper trafficking and its relationship with ceruloplasmin synthesis. Symptomatic patients may present with hepatic, neurologic or psychiatric forms. Clinical and phenotypic evidences provide only presumptive arguments for this disease which can be routinely assessed by molecular analysis. This genetic disease which can be efficiently treated was formerly biologically suspected after a careful but sometimes invasive study of copper metabolism. Genetic advances can now give a definite answer using linkage analysis and research for disease-causing mutations. However, this diagnosis strategy is limited since currently over 320 mutations and 80 polymorphisms have been currently identified.

A 10 year follow up study of patients transplanted for autoimmune hepatitis: histological recurrence precedes clinical and biochemical recurrence

BACKGROUND AND AIM

Autoimmune hepatitis (AIH) has been reported to recur after orthotopic liver transplantation (OLT) in 10-35% of patients in small series with a short follow up. The aim of the present study was to examine the clinical and histological outcome more than 10 years after OLT for AIH.

PATIENTS AND METHODS

Seventeen women with a mean age of 30 (12) years at the time of OLT, selected from among 44 patients transplanted for AIH, were followed for more than 10 years. The criteria for definite AIH, as established by the International Autoimmune Hepatitis Group, were met in every case. Liver biopsies were performed 1, 2, 5, and 10 years after OLT, and when indicated by abnormal liver function tests. Specimens were examined for evidence of recurrent AIH, namely interface hepatitis, lobular activity, portal lymphoplasmocytic infiltration, and fibrosis. Other signs of recurrence included hypertransaminasaemia, serum autoantibodies, and the response to steroid reintroduction or significant steroid dose increments.

RESULTS

AIH recurred in 7 (41%) of 17 patients. In four patients histological abnormalities were detected by means of protocol biopsies 1-5 years before the onset of biochemical abnormalities. Two patients developed severe recurrences after 10 and 15 years, respectively, and required treatment with steroids and tacrolimus. In the other three patients histological recurrence was detected 0.6-3 years post-OLT, concomitantly with biochemical abnormalities.

CONCLUSIONS

AIH recurred in 41% of patients followed for more than 10 years after OLT. As histological signs preceded biochemical abnormalities in four patients (23.5%), regular liver biopsy is warranted after OLT. Detection of isolated histological signs may call for closer follow up and/or a change in immunosuppressive therapy.

Residual hepatitis B virus particles in liver transplant recipients receiving lamivudine: PCR quantitation of HBV DNA and ELISA of preS1 antigen

Lamivudine, an antiviral agent, has a potential role in the treatment of recurrent or acquired de novo hepatitis B virus (HBV) infection after liver transplantation. During lamivudine therapy, residual HBV particles in serum, PBMC, and liver were quantified in 7 patients in whom hepatitis B occurred de novo (n = 4) or recurred (n = 3). HBV DNA and preS1 antigen were measured using a sensitive PCR technique and an in-house ELISA method, respectively. The genetic and antigenic properties of HBV variants that emerged during lamivudine treatment were also examined. One month after the outset of lamivudine treatment, all 7 patients remained positive for both HBV DNA and preS1 antigen in serum, reflecting residual HBV replication. At the end of therapy, four patients were considered to be lamivudine responders, including one who seroconverted to anti-HBs but remained HBV DNA positive in the liver (> 10(3) copies/microg of DNA). Among the three patients who did not respond to lamivudine, one had pol mutations (L450P and S550C) that had not been described previously, in addition to the common mutations within the YMDD locus and B domain. Defective core and preS viral proteins and atypical sedimentation profiles of HBV DNA-positive particles were observed in all three lamivudine-resistant patients. These findings confirm the persistence of HBV in liver transplant recipients despite strong inhibition of replication by lamivudine, and show abnormal viral transcription and/or morphogenesis in lamivudine-resistant patients.

[Autoimmune hepatitis. Physiopathologic, clinical, histological, and therapeutic features]

Autoimmune hepatitis is characterized by an inflammation of the portal tract with lymphocytes and plasma cells, an hypergammaglobulinemia and a variety of circulating autoantibodies. The presence of smooth muscle antibodies and/or antinuclear antibodies define type 1. Type 2 is characterized by the presence of liver-kidney--microsomal antibodies. Environmental, genetic and infectious factors may explain the autoreactivity of T cells. Different non specific clinical features may be present. Sometimes the presentation may be an acute hepatitis; in the remainder, the disease may not be recognized until liver damage is advanced. Hypergammaglobulinemia and presence of circulating autoantibodies are the key for diagnosis. The association of prednisolone in combination with azathioprine remains the established treatment. If relapse or non response occur, other immunosuppressive therapy such as cyclosporin may be useful. Liver transplantation is reserved for (sub)fulminant forms and end stage liver disease.

[Radiation-induced stricture of the papilla and the common bile duct: successful treatment with balloon dilation]

Radiation-induced lesions of the bile ducts rarely occur and may be difficult to manage. We report the case of a 59-year old woman who developed radiation-induced stenosis of the papilla and the common bile duct 25 years after abdominal radiation therapy for abdominal non-Hodgkin's lymphoma. She presented with recurrent cholangitis and chronic cholestasis. Endoscopic results showed dilation of the intrahepatic bile ducts, radiation-induced inflammation and narrowing of the antrum and the duodenum, and stricture of the papilla and the last few millimeters of the common bile duct. The patient was treated with endoscopic balloon dilation. Forty-two months after endoscopic dilation, the patient remained asymptomatic with normal liver tests and no biliary dilation at ultrasound.

[Adult to adult living-related liver transplantation. The Paul-Brousse Hospital preliminary experience]

AIM

Liver-graft shortages justify the development of adult living-related liver transplantation. The preliminary experience with this technique at Paul-Brousse Hospital is reported. PATIENTS ET METHODES: From January to July 2000, 7 adult to adult living-related liver transplantations were performed. Donors were 5 females and 2 males aged 20 to 53 years old (median: 41). A right liver graft was harvested in all cases. Recipients were 5 males and 2 females aged from 17 to 58 years old (median: 50) transplanted for viral cirrhosis (4 cases including 2 with hepatocellular carcinoma), subfulminant hepatitis (1 case), hepatocellular carcinoma on a healthy liver (1 case), and epithelioid hemangioendothelioma (1 case). Follow-up ranged from 41 to 157 days (median: 117 days).

RESULTS

One donor had a biliary fistula that healed spontaneously. One donor had asterixis for 24 hours. The 7 donors are alive at home without any late complications. One recipient was retransplanted for hepatic artery thrombosis and 2 recipients had a biliary fistula that healed spontaneously. The 7 recipients are alive at home with normal liver function.

CONCLUSION

Our experience and other reports suggest that adult to adult living-related liver transplantation is feasible with rare mortality and low morbidity in donors. Results in recipients are comparable to those obtained with cadaveric grafts. For a given patient the possibility of living related donation might extend the indications for transplantation without penalizing patients waiting for a cadaveric graft.

Successful tacrolimus therapy for a severe recurrence of type 1 autoimmune hepatitis in a liver graft recipient

A 34-year-old woman underwent orthotopic liver transplantation (OLT) for decompensated type 1 autoimmune hepatitis (AIH). She was administered standard triple-drug immunosuppressive therapy (cyclosporine, steroids, and azathioprine). Ten years after OLT, she developed a recurrence of AIH, with emergence of serological markers of autoimmunity (high anti--smooth muscle antibody [ASMA] titer, high serum gamma globulin level), abnormal liver function test results, and characteristic histological features on liver biopsy. Despite intensified steroid therapy, her clinical and liver function deteriorated. The onset of cutaneous alternariosis led to a steroid dose reduction and cyclosporine replacement by tacrolimus. Clear-cut amelioration was observed, with an improvement in liver function test results and reduction in ASMA titer. One year after the recurrence of AIH, the patient has normal liver function and physical findings. Tacrolimus therefore may be effective in patients with severe recurrent autoimmune liver disease. Further studies are needed to assess tacrolimus therapy in patients who fail to respond to standard immunosuppressive therapy.

Evaluation of an enzyme-linked immunosorbent assay for detection and quantification of hepatitis B virus PreS1 envelope antigen in serum samples: comparison with two commercial assays for monitoring hepatitis B virus DNA

An in-house sensitive and easy-to-use solid-phase enzyme-linked immunoassay (ELISA) was adapted for the detection and quantification of hepatitis B virus (HBV) PreS1 envelope antigen in serum, and compared with the HBV DNA Hybrid Capturetrade mark system from Murex and the polymerase chain reaction (PCR) Amplicortrade mark HBV Monitor assay from Roche. Twenty-five patients with chronic hepatitis B after liver transplantation were included in this study. The sensitivity of our ELISA was found to be 50 pg of HBsAg/PreS1Ag ml-1. The linearity was between 0.1 and 100 ng ml-1. Intra-assay reproducibility was obtained with a standard deviation of <1%. No correlation between the presence of serum PreS1 antigen and viral DNA detected by direct hybridization (Murex) was observed. In contrast, there was a significant 96% correspondence in the presence of PreS1 antigen and viral DNA detected and quantified by the PCR assay (Roche). In conclusion, the most important and reliable markers for monitoring residual HBV replication in serum were HBV DNA by the PCR assay, and virus envelope PreS1Ag by our in-house ELISA. Thus, PreS1Ag disappearance in serum could be used for evaluating the efficacy of antiviral therapies.

Complete remission of unresectable hepatocellular carcinoma on healthy liver by the combination of aggressive surgery and high-dose-intensity chemotherapy by CPT-11

Hepatocellular carcinoma (HCC) is one of the most frequent cancers. The only curative treatment is liver transplantation or complete surgical resection; however, most patients have inoperable disease at diagnosis. To date, no cytotoxic agent has demonstrated a clinical impact on time-related parameters, especially survival. The development of new treatments of inoperable HCC patients is highly desirable. Among the new cytotoxic agents, DNA topoisomerase I poisons are those with the widest spectrum of antitumor activity. However, few data are available in HCC patients. One of the main obstacles to the use of irinotecan in HCC is the frequent alterations of liver function at diagnosis. A 48-year-old patient with a HCC that had developed within a normal liver but of very poor prognosis because of a multifocal primary tumor with a large nodule measuring 10 cm of diameter, associated with a portal thrombosis, could tolerate very intensive treatment with irinotecan using doses up to 700 mg/m2 every 2 weeks and was responsive to treatment as measured by alpha-fetoprotein levels. Despite initial criteria of inoperability, the absence of disease progression under therapy with a follow-up of 1 year invited us to propose a liver transplant. The patient is still in post-surgical complete remission and has consolidation chemotherapy with irinotecan. This result invites us to consider the evaluation of the efficacy of topoisomerase I poisons in HCC patients and to escalate the dose of irinotecan in patients with less than grade 4 neutropenia.

Autoantibodies associated with acute rejection after liver transplantation for type-2 autoimmune hepatitis

Autoantibodies, markers of autoimmune diseases, can also be detected in chronic allograft rejection. However, the appearance of these autoantibodies in acute rejection after orthotopic liver transplantation has not yet been reported. Liver-kidney-microsome type-1 (LKM-1) antibodies directed against the autoantigen cytochrome CYP2D6 define a group of patients with autoimmune hepatitis type-2 (AIH-2), distinct from autoimmune hepatitis type-1 (AIH-1) in which anti-nuclear antibodies and anti-smooth muscle antibodies (SMA) with actin specificity are present in patient sera. Autoantibodies were studied by the quantitative CYP2D6 radioligand assay (RLA) that uses a radiolabeled CYP2D6 as antigen, immunoblotting using recombinant CYP2D6 protein and human liver microsomal and cytosolic fractions, and indirect immunofluorescence (IIF) using rat kidney-stomach-liver cryostat sections. In addition, the specificity of anti-SMA was detected by IIF on HEp2 cell line harvested with colchicin. This report describes the time course of CYP2D6 antibodies and the appearance of anti-SMA (without anti-actin, cytokeratin and vimentin reactivity) associated with acute rejection during a 2-year follow-up, in a patient who underwent transplantation at end-stage type 2 autoimmune hepatitis. In addition, we report a new reactivity against an unknown 40-kDa protein using a rat cytosolic fraction. The detection of autoantibodies in sequential samples may be important to better predict rejection or relapse, and to establish adequate therapy.

Phosphorylation of the hepatitis B virus core protein by glyceraldehyde-3-phosphate dehydrogenase protein kinase activity

In order to characterize the hepatitis B virus (HBV) hepatocellular receptor, several proteins have previously been identified in HepG2 hepatoma cells and in primary cultured normal human hepatocytes (PCHs) that reacted with an anti-idiotypic antibody against a preS1(21-47)-specific MAb (F35.25). Here, we report the identification of one of these preS1-binding proteins, a 35 kDa protein (preS1-BP35), as glyceraldehyde-3-phosphate dehydrogenase (GAPD). GAPD is well-known as a key enzyme involved in glycolysis and gluconeogenesis. Nevertheless, GAPD has also been shown to have many other functions such as protein kinase activity (GAPD-PK). HBV core particles derived from infected hepatocytes possess an associated kinase activity that phosphorylates HBcAg, and the nucleocapsid may acquire sequential functions through selective phosphorylation. Therefore, we have investigated the potential role of GAPD-PK in HBV replication. In this study, we found that the endogenous PK associated with human liver-derived HBV core particles (hL-HBcAg) and GAPD-PK were sensitive to the same types of inhibitors. Interestingly, capsid protein phosphorylation decreased in a concentration-dependent manner (at concentrations of 5-30 mM) in the presence of specific inhibitors for GAPD-PK (NADH and GAP). Furthermore, we demonstrated in vitro that GAPD-PK could phosphorylate the major core protein P22 in hL-HBcAg particles. The data suggest that GAPD is an additional cellular kinase which might interfere in the life-cycle of HBV.

Interferon therapy in LKM-1 positive patients with chronic hepatitis C: follow-up by a quantitative radioligand assay for CYP2D6 antibody detection

BACKGROUND/AIMS

Liver/kidney microsomal type 1 (LKM-1) antibodies described by indirect immunofluorescence using frozen sections of kidney, stomach and rat liver define a group of patients with type 2 autoimmune hepatitis. Sera react with a non-glycosylated 50-kD protein of the endoplasmic reticulum, which was recently identified as cytochrome P4502D6 (CYP2D6). LKM-1 antibodies may also be associated with hepatitis C virus infection (HCV+/LKM-1+). For this subset of patients, the choice of steroids or interferon alpha therapy may be difficult because of the association of hepatitis C virus infection and autoimmune manifestations. Recently we developed a quantitative immunoprecipitation radioligand assay using 35S-methionine-labeled CYP2D6 protein produced by in vitro transcription and translation reaction. This method detects antibodies against linear and conformational epitopes in both AIH-2 and HCV+/LKM-1+ patients. The aim of this study was to analyze the time-course of HCV+/LKM-1+ patients, applying our radioligand assay over a long follow-up.

METHODS

We studied five patients who were positive for CYP2D6 antibodies from among 235 chronic hepatitis C virus hepatitis patients (2.1%) treated with interferon alpha for a minimal follow-up of 2 years. We analyzed LKM-1 antibody titer sequentially by radioligand assay, HCV RNA titer and alanine aminotransferase activity in these patients.

RESULTS

We found no aggravation of liver disease in this group of patients. Three of these patients showed a sustained biochemical and virological response after interferon. Two others responded partially to interferon therapy. Alanine aminotransferase levels and HCV-RNA decreased during interferon therapy in responder patients. CYP2D6 antibodies did not change in three responder patients during follow-up. One responder patient decreased CYP2D6 antibody level by radioligand assay, but indirect immunofluorescence titers showed a similar pattern. One partial responder patient decreased CYP2D6 antibody level but was negative by indirect immunofluorescence.

CONCLUSIONS

Our results show that patients with hepatitis C virus who are positive for CYP2D6 antibodies may be treated with interferon, and respond in the same way as CYP2D6 antibody negative patients. Radioligand assay could be helpful for monitoring HCV+/LKM-1+ patients receiving interferon therapy.

Primary biliary cirrhosis-autoimmune hepatitis overlap syndrome. Corticoresistance and effective treatment by cyclosporine A

We report a case of primary biliary cirrhosis-autoimmune hepatitis overlap syndrome treated with cyclosporine A. Features of primary biliary cirrhosis were pruritus, high titer of antimitochondrial antibodies, inflammatory infiltrates surrounding interlobular bile ducts, and periportal granuloma. Features suggestive of autoimmune hepatitis were high titer of antinuclear antibodies, very high total immunoglobulins, and piecemeal necrosis. Because corticosteroids and ursodeoxycholic acid were inefficient, cyclosporine A was started at a dose of 3 mg/kg/day. A dramatic improvement in clinical condition, liver tests, and histology was noted. Discontinuation of cyclosporine A was followed by a clinical and histological relapse. Cyclosporine A reintroduction was again associated with a significant improvement. This case report suggests that in corticoresistant cases cyclosporine A could be an effective therapy for primary biliary cirrhosis-autoimmune hepatitis overlap syndrome.

Conformational epitopes on CYP2D6 are recognized by liver/kidney microsomal antibodies

BACKGROUND/AIMS

Four linear antigenic sites have been shown on the CYP2D6 molecule that are recognized by serum positive for liver/kidney microsomal antibody (LKM) type 1. The aim of this study was to search for antibodies against CYP2D6 conformational antigenic sites in LKM-1-positive sera.

METHODS

The capacity of four LKM-1-positive sera, before and after absorption with synthetic peptides representing CYP2D6 linear antigenic sites, and rabbit sera against linear antigenic sites between CYP2D6 amino acids 254-271 and 373-389 to inhibit the O-demethylation of dextromethorphan by CYP2D6 was tested in vitro.

RESULTS

Inhibition of O-demethylation of dextromethorphan was not modified by absorption of antibodies against linear CYP2D6 antigenic sites. In addition, rabbit sera against two of these sites did not inhibit the reaction. These results strongly suggest that antibodies against CYP2D6 conformational antigenic sites were present in LKM-1-positive sera.

CONCLUSIONS

The autoimmune response against CYP2D6 is directed against linear and conformational antigenic sites. These results strengthen the argument that the LKM-1 response is polyclonal and antigen driven.