Outcomes of normothermic machine perfusion of liver grafts in repeat liver transplantation (NAPLES initiative).

BACKGROUND: Retransplantation candidates are disadvantaged owing to lack of good-quality liver grafts. Strategies that can facilitate transplantation of suboptimal grafts into retransplant candidates require investigation. The aim was to determine whether late liver retransplantation can be performed safely with suboptimal grafts, following normothermic machine perfusion. METHODS: A prospectively enrolled group of patients who required liver retransplantation received a suboptimal graft preserved via normothermic machine perfusion. This group was compared with both historical and contemporaneous cohorts of patient who received grafts preserved by cold storage. The primary outcome was 6-month graft and patient survival. RESULTS: The normothermic machine perfusion group comprised 26 patients. The historical (cold storage 1) and contemporaneous (cold storage 2) groups comprised 31 and 25 patients respectively. The 6-month graft survival rate did not differ between groups (cold storage 1, 27 of 31, cold storage 2, 22 of 25; normothermic machine perfusion, 22 of 26; P = 0.934). This was despite the normothermic machine perfusion group having significantly more steatotic grafts (8 of 31, 7 of 25, and 14 of 26 respectively; P = 0.006) and grafts previously declined by at least one other transplant centre (5 of 31, 9 of 25, and 21 of 26; P < 0.001). CONCLUSION: In liver retransplantation, normothermic machine perfusion can safely expand graft options without compromising short-term outcomes.

Liver transplantation is a life-saving procedure for many different diseases. In the UK, one in 10 patients awaiting transplant have had a previous liver transplant. These retransplant operations are complex, and the general belief is that a good-quality donor liver graft is required for best outcomes. However, there is a significant shortage of good-quality organs for liver transplantation, so many patients awaiting retransplantation spend longer on the waiting list. This study investigated whether a new technology, called normothermic machine perfusion, could be used to preserve lower-quality donor livers and have successful outcomes for patients undergoing retransplantation. Traditionally, good-quality livers are preserved in an ice box and the study compared the outcomes of these two different approaches. The aim was to prove that normothermic machine perfusion improves access to transplantation for this group of patients, without compromising outcomes. A group of patients who underwent retransplantation and received a lesser-quality liver preserved with normothermic machine perfusion was compared with two groups of patients who had received a transplant with traditional ice-box preservation. The complications, graft, and patient survival of the former group was compared with those in the latter two groups who underwent liver retransplantation with better-quality liver grafts. The rate of survival and adverse surgical outcomes were comparable between the groups of patients who received a liver preserved via traditional ice-box preservation, and those who received a lesser-quality liver preserved via normothermic machine perfusion. Normothermic machine perfusion can potentially expand the number of suitable donor livers available for retransplant candidates.

New treatments for hepatitis C virus (HCV): scope for preventing liver disease and HCV transmission in England.

New direct-acting antivirals have the potential to transform the hepatitis C (HCV) treatment landscape, with rates of sustained viral response in excess of 90%. As these new agents are expensive, an important question is whether to focus on minimizing the consequences of severe liver disease, or reducing transmission via 'treatment as prevention'. A back-calculation model was used to estimate the impact of treatment of mild, moderate and compensated cirrhosis on incident cases of HCV-related end-stage liver disease/hepatocellular carcinoma (ESLD/HCC). In addition, a dynamic model was used to determine the impact on incidence and prevalence of chronic infection in people who inject drugs (PWID), the main risk group in England. Treating 3500 cirrhotics per year was predicted to reduce ESLD/HCC incidence from 1100 (95% CrI 970-1240) cases per year in 2015 to 630 (95% CrI 530-770) in 2020, around half that currently expected, although treating moderate-stage disease will also be needed to sustain this reduction. Treating mild-stage PWID was required to make a substantial impact on transmission: with 2500 treated per year, chronic prevalence/annual incidence in PWID was reduced from 34%/4.8% in 2015 to 11%/1.4% in 2030. There was little overlap between the two goals: treating mild stage had virtually no impact on ESLD/HCC within 15 years, but the long timescale of liver disease means relatively few PWID reach cirrhosis before cessation of injecting. Strategies focussing on treating advanced disease have the potential for dramatic reductions in severe morbidity, but virtually no preventative impact.

Outcome of liver transplantation in patients with hereditary bleeding disorders: a single centre UK experience.

INTRODUCTION: Patients with hereditary bleeding disorders who have developed end-stage liver disease as a consequence of hepatitis C infection (HCV) acquired from factor concentrates prior to the introduction of viral inactivation continue to be referred for liver transplantation. METHODS: A retrospective review of case notes and electronic records was performed on all patients with bleeding disorders who have undergone liver transplantation at the University Hospital Birmingham (UHB). RESULTS: Between 1990 and 2014, 35 liver transplants have been performed in 33 patients with hereditary bleeding disorders. The indication for transplantation was mainly end-stage liver disease secondary to HCV. Five patients had human immunodeficiency virus (HIV) co-infection. No excess mortality due to bleeding occurred in the peri or postoperative period. Median overall survival post transplant is 9.7 years. Overall survival rates at 1, 3 and 5 years are 90%, 72% and 64% respectively. The predominant cause of mortality was liver failure secondary to either recurrent HCV or recurrent hepatocellular carcinoma (HCC). The median overall survival in patients with HIV co-infection is shorter than in those with mono-infection but this is not statistically significant. Patients with a pre-existing HCC had a statistically significant shorter survival (2.4 years vs. 13.6 years, P = 0.007). CONCLUSION: Liver transplantation has become an accepted treatment option for patients with hereditary bleeding disorders and HCV associated end-stage liver disease with survival rates similar to non-bleeding disorder patients.

Operator training requirements and diagnostic accuracy of Fibroscan in routine clinical practice.

BACKGROUND: Fibroscan is a quick, non-invasive technique used to measure liver stiffness (kPa), which correlates with fibrosis. To achieve a valid liver stiffness evaluation (LSE) the operator must obtain all the following three criteria: (1) ≥10 successful liver stiffness measurements; (2) IQR/median ratio <0.30 and (3) ≥60% measurement success rate. OBJECTIVES: To assess the operator training requirements and the importance of adhering to the LSE validity criteria in routine clinical practice. METHODS: We retrospectively analysed the LSE validity rates of 2311 Fibroscans performed (1 August 2008 to 31 July 2011) in our tertiary liver outpatients department at the University Hospital Birmingham, UK. The diagnostic accuracy of Fibroscan was assessed in 153 patients, by comparing LSE (valid and invalid) with the modified Ishak fibrosis stage on liver biopsy. RESULTS: Learning curve analysis highlighted that the greatest improvement in validity of LSE rates occurs in the operator's first 10 Fibroscans, reaching 64.7% validity by the 50th Fibroscan. The correlation between LSE and the fibrosis stage on liver biopsy was superior in patients with a valid LSE (n=97) compared with those with an invalid LSE (n=56) (rs 0.577 vs 0.259; p=0.022). Area under receiving operating characteristics for significant fibrosis was greater when LSE was valid (0.83 vs 0.66; p=0.048). Using an LSE cut-off of 8 kPa, the negative predictive value of valid LSE was superior to invalid LSE for the detection of significant (84% vs 71%) and advanced fibrosis (100% vs 93%). CONCLUSIONS: Fibroscan requires minimal operator training (≥10 observed on patients), and when a valid LSE is obtained, it is an accurate tool for excluding advanced liver fibrosis. To ensure the diagnostic accuracy of Fibroscan it is essential that the recommended LSE validity criteria are adhered to in routine clinical practice.

UKHCDO guidelines on the management of HCV in patients with hereditary bleeding disorders 2011.

Chronic HCV infection continues to be of significant clinical importance in patients with hereditary bleeding disorders. This guideline provides information on the recent advances in the investigation and treatment of HCV infection and gives GRADE system based recommendations on the management of the infection in this patient group.

Incidence and characterization of serum transaminases elevations in pegylated interferon and ribavirin treated patients with chronic hepatitis C.

BACKGROUND: A virological response to pegylated-interferon and ribavirin is typically associated with a prompt fall in serum transaminases. For some patients, transaminases rise during treatment. AIM: To assess the frequency and define factors associated with elevations of serum transaminases. METHODS: A total of 169 treated patients were studied. Transaminase elevations were graded by WHO criteria - grade 0: no value > baseline, grade 1: 1-2x baseline, grade 2: 2.1-5x baseline, grade 3: >5x, grade 4: any rise with evidence of liver failure. Results 60/169 (35%) patients experienced transaminase elevations: 52 grade 1, 6 grade 2, 1 grade 3, 1 grade 4. Overall, end of treatment response and sustained virological response rates were 72% and 55%. Lower rates were observed in the grade 1 elevation group (63% and 40%) compared with patients with grade 0 (79% and 65%) and grade > or =2 elevations (85% and 71%). Grade 1 elevations tended to occur earlier during treatment than grade > or =2 elevations. Transaminase elevations were associated with greater pre-treatment body weight (P = 0.006), steatosis (P = 0.008) and poorer sustained virological response rates (P = 0.007). CONCLUSIONS: Transaminase elevations during treatment of chronic Hepatitis C virus with pegylated interferon and ribavirin are common but rarely severe. Mild rises may reflect ongoing viral activity in treatment non-responders. More significant rises are frequently observed despite a virological response, and may be because of an immuno-modulating effect of interferon in susceptible patients.

Primary hepatocellular cancer in the explanted liver: outcome of transplantation and risk factors for HCC recurrence.

AIM: To evaluate the risk of recurrence of hepatocellular cancer (HCC) after liver transplantation (LT). METHODS: The clinical records of 104 patients with HCC in the explanted liver were examined. RESULTS: HCC recurrence occurred in 12 patients. Recurrence was observed in all patients with a single nodule greater than 5 cm. Among the 5 patients with more than 3 tumours with a maximum diameter of 4.5 cm, no recurrence occurred. The survival rates were 81% and 64% at 1 and 5 years, respectively; the recurrence-free survival at 1 and 5 years was, respectively, 93% and 82%. Pre-LT alpha-fetoprotein (AFP) increased at a greater magnitude in patients who experienced recurrence, compared to those who did not. Tumour diameter, differentiation, satellitosis, AFP and the magnitude of AFP increase were predictive of recurrence. The 1- and 5-year recurrence-free survival for the 68 patients who had a single nodule up to 5 cm, or up to 3 nodules all less than 4.5 cm and with a maximum cumulative diameter of 8 cm, or more than 3 nodules all less than 2.5 cm, were 95% and 92%, respectively. For the 13 patients not meeting these criteria, the 1- and 5-year recurrence-free survival was, respectively, 75% and 54% (log Rank test p=0.019). CONCLUSIONS: Patients with more than 3 small HCC nodules before LT could still have a good outcome without recurrence. A rapid increase in AFP could be useful in identifying patients with a greater risk of post-LT HCC recurrence.

Hepatitis C Virus Recurrence Occurs Earlier in Patients Receiving Donation After Circulatory Death Liver Transplant Grafts Compared With Those Receiving Donation After Brainstem Death Grafts.

INTRODUCTION: Hepatitis C virus (HCV)-related cirrhosis remains the commonest indication for liver transplantation worldwide, yet few studies have investigated the impact of donation after circulatory death (DCD) graft use on HCV recurrence and patient outcomes. DCD grafts have augmented the limited donor organ pool and reduced wait-list mortality, although concerns regarding graft longevity and patient outcome persist. METHODS: This was a single-center study of all HCV + adults who underwent DCD liver transplantation between 2004 and 2014. 44 HCV+ patients received DCD grafts, and were matched with 44 HCV+ recipients of donation after brainstem death (DBD) grafts, and their outcomes examined. RESULTS: The groups were matched for age, sex, and presence of hepatocellular carcinoma; no significant differences were found between the group's donor or recipient characteristics. Paired and unpaired analysis demonstrated that HCV recurrence was more rapid in recipients of DCD organs compared with DBD grafts (408 vs 657 days; P = .006). There were no significant differences in graft survival, patient survival, or rates of biliary complications between the cohorts despite DCD donors being 10 years older on average than those used in other published experience. CONCLUSIONS: In an era of highly effective direct acting antiviral therapy, rapid HCV recrudescence in grafts from DCD donors should not compromise long-term morbidity or mortality. In the context of rising wait-list mortality, it is prudent to use all available sources to expand the pool of donor organs, and our data support the practice of using extended-criteria DCD grafts based on donor age. Notwithstanding that, clinicians should be aware that HCV recrudescence is more rapid in DCD recipients, and early post-transplant anti-viral therapy is indicated to prevent graft injury.

Review article: hepatitis B and liver transplantation.

Liver transplantation is an excellent treatment for hepatitis B virus infected patients who have acute or chronic liver failure and/or primary liver cancer. Advances in antiviral prophylaxis prevent clinically significant graft re-infection for the majority of patients. Graft and patient survival has improved significantly during the past decade, and results of transplantation for hepatitis B virus are now superior to those achieved for most other indications. In particular, the availability of lamivudine and adefovir have transformed outcome. The addition of lamivudine to passive immunoprophylaxis with hepatitis B virus immunoglobulin prevents re-infection in most cases. Adefovir should be added to this combination when the patient develops lamivudine resistance before transplantation. The significance of serum hepatitis B virus DNA positivity in the absence of circulating hepatitis B surface antigen is uncertain. Hepatitis B virus infection of the graft can be observed when prophylaxis is inadequate, when the donor liver contains latent hepatitis B virus infection (so-called de novo infection from the hepatitis B virus core antibody positive donor), and when the donor is exposed to third party infection (sexual or nosocomial transmission). Established hepatitis B virus graft infection is a good indication for combination nucleoside analogue therapy. Combination therapy can achieve sustained suppression of viral replication, and hepatitis B e antigen and hepatitis B surface antigen clearance can also be observed.

Randomised clinical trial: alisporivir combined with peginterferon and ribavirin in treatment-naïve patients with chronic HCV genotype 1 infection (ESSENTIAL II).

BACKGROUND: Alisporivir (ALV) is an oral, host-targeting agent with pangenotypic anti-hepatitis C virus (HCV) activity and a high barrier to resistance. AIM: To evaluate efficacy and safety of ALV plus peginterferon-α2a and ribavirin (PR) in treatment-naïve patients with chronic HCV genotype 1 infection. METHODS: Double-blind, randomised, placebo-controlled, Phase 3 study evaluating ALV 600 mg once daily [response-guided therapy (RGT) for 24 or 48 weeks or 48 weeks fixed duration] or ALV 400 mg twice daily RGT with PR, compared to PR alone. Following a Food and Drug Administration partial clinical hold, ALV/placebo was discontinued and patients completed treatment with PR only. At that time, 87% of patients had received ≥12 weeks and 20% had received ≥24 weeks of ALV/PR triple therapy. RESULTS: A total of 1081 patients were randomised (12% cirrhosis, 55% CT/TT IL28B). Addition of ALV to PR improved virological response in a dose-dependent fashion. Overall, sustained virological response (SVR12; primary endpoint) was 69% in all ALV groups vs. 53% in PR control. Highest SVR12 (90%) was achieved in patients treated with ALV 400 mg twice daily and PR for >24 weeks. Seven cases of pancreatitis were reported, with similar frequency between ALV/PR and PR control groups (0.6% vs. 0.8% respectively). Adverse events seen more frequently with ALV/PR than with PR alone were anaemia, thrombocytopenia, hyperbilirubinaemia and hypertension. CONCLUSIONS: Alisporivir, especially the 400 mg twice daily regimen, increased efficacy of PR therapy in treatment-naïve patients with HCV genotype 1 infection. The mechanism of action and pangenotypic activity suggest that alisporivir could be useful in interferon-free combination regimens.

Hepatitis B virus antiviral drug resistance: from the laboratory to the patient.

The development and application of nucleoside (and nucleotide) analogues for the treatment of chronic hepatitis B infection will transform the management of this condition. For instance, treatment with lamivudine effects a dramatic and measurable reduction of serum virus titre. This is associated with biochemical and histological improvements. Unfortunately, for the majority, replication resumes when treatment is withdrawn. Prolonged lamividine treatment may be associated with the emergence of drug-resistant species with specific polymerase mutations. Compared with the observed rate for the development of drug resistance observed during monotherapy of HIV infection, resistance is slow to emerge during treatment of hepatitis B. The rate of emergence might be dependent on the rate of infected hepatocyte turnover, which is extremely variable in chronic HBV infection (and significantly slower than infected lymphocyte turnover during HIV infection). Preliminary data suggest that pretreatment serum virus titre may be an important predictor of the development of drug resistance, an observation consistent with preexistance of the resistant virus in the hepatitis B virus quasispecies. Akin to developments in antiviral treatment of HIV infection, further progress in the treatment of chronic hepatitis B will depend on the development of drugs for use in combination therapy.

Analysis of hepatitis B virus quasispecies changes during emergence and reversion of lamivudine resistance in liver transplantation.

This report describes nucleotide sequence analysis of part of the polymerase gene of hepatitis B virus (HBV) during the development of lamivudine-resistant HBV in five patients who received lamivudine treatment in conjunction with liver transplantation. Samples from patients were analysed before, during and after drug treatment in conjunction with serum HBV quantification by PCR. Lamivudine resistance was found to be associated with L526M and M550V changes in two patients and M550I change in three patients. Other changes associated with lamivudine resistance in some patients were V509I, A546V, S565A and A568T. The effects on HBV surface antigen are also described. Some patients were subsequently treated with famciclovir and/or ganciclovir with variable outcomes. In two out of three patients who stopped lamivudine treatment, reversion (partial or complete) to wild-type virus was observed after about 5 months. In contrast, a complex mixture of mutant viruses emerged in a third patient who stopped lamivudine treatment.

Additive antiviral effects of lamivudine and alpha-interferon in chronic hepatitis B infection.

alpha-Interferon has limited efficacy against chronic hepatitis B virus (HBV) infection. Nucleoside analogues may confer greater benefits, however, it is likely that combination therapies will be required for effective control of this infection. We investigated the antiviral effect of lamivudine and interferon therapy in eight patients with high HBV-DNA levels. Six patients received lamivudine/interferon combination therapy followed, after a 6-month drug-free period, with lamivudine monotherapy. Mean HBV viral load (copies/ml) reduction was significantly greater after 4 months of combination therapy (4.3 x 10(3)) compared to an equivalent period of lamivudine monotherapy (2.9 x 10(2)) (P=0.03). Two patients were given 6 months of lamivudine/interferon combination therapy followed immediately by lamivudine monotherapy. Cessation of interferon in these patients led to a rapid 1-2 log10 increase in HBV viral load. These findings suggest that alpha-interferon has a direct antiviral effect on chronic HBV infection, which may be additive to, or synergistic with lamivudine.

Enhanced (cytomegalovirus) viral replication associated with septic bacterial complications in liver transplant recipients.

BACKGROUND: Complications of the biliary anastomosis are the principal cause of clinically serious bacterial sepsis in liver transplant recipients. Reported series suggest an association of bacterial and fungal infection with cytomegalovirus (CMV) infection, although the mechanism of this association is unclear. METHODS: We examined the association of serious bacterial sepsis with CMV replication in a cohort of 106 consecutive liver transplant recipients. Sequentially collected buffy coats were examined with a polymerase chain reaction (PCR) assay that has been shown to have good predictive value for the development of CMV infection. For selected patients, CMV-specific IgM response and serum tumor necrosis factor-alpha (TNF-alpha) were also measured. RESULTS: Ten of 13 patients with serious bacterial sepsis developed buffy coat PCR positivity, compared with 26 of 93 patients without bacterial sepsis (chi-square, P<0.001). Ten of 10 septic recipients with a seropositive liver donor developed PCR positivity. For 9 of 10 recipients, bacterial sepsis developed before PCR positivity. Bacterial sepsis was associated with high serum levels of TNF-alpha. Immune response to CMV (reflected by the appearance CMV-specific IgM) was apparently affected by bacterial sepsis, and IgM response was not observed for the three septic patients who died during the study period. CONCLUSIONS: We conclude that CMV replication is encouraged by serious bacterial sepsis. Replication may be promoted by high antecedent levels of TNF-alpha, and/or by poor immune response to CMV in the context of serious bacterial infection.

Patterns of viremia in liver transplant recipients with symptomatic cytomegalovirus infection.

Cytomegalovirus (CMV) titer in blood seems to be the principal determinant of clinical symptoms in immunosuppressed patients. We have developed an assay for quantitation of CMV DNA in serum. The assay requires the coamplification by polymerase chain reaction (PCR) of extracted serum DNA with 1000 molecules of mutated internal standard DNA, and then an ELISA detection system. We examined 133 paired buffy coats and sera from 15 patients with symptomatic infection. Sera were examined by quantitative PCR, and buffy coats were examined by qualitative PCR (with a detection threshold of approximately 40 copies per 150,000 cells). Serum viral titers peaked during the seventh week after transplant (median day 40, range 26-58) at about the time of symptom onset. Mean viral titer measured during the seventh week was 1.2 x 10(5) copies per milliliter of serum (standard error 6.5 x 10(4). Buffy-coat PCR results were generally concordant with results of serum PCR (overall concordance 103/133=77.4%). Serum CMV titer fell, as symptoms resolved with reduction of immunosuppression and specific antiviral therapy. High titers and poor response to antiviral therapy were observed in the context of excessive immunosuppression and bacterial sepsis. Measurement of serum CMV titer may be useful for the management of immunosuppressed transplant recipients, and provides a tool for the better understanding of factors that enhance or inhibit viral replication.

Quantitation of Epstein-Barr virus DNA in the blood of adult liver transplant recipients.

BACKGROUND: Posttransplant lymphoproliferation is most often observed in pediatric transplant recipients who experience primary Epstein-Barr virus (EBV) infection at the time of or after transplantation. Lymphoproliferation is believed to be caused by impaired control of EBV-infected cells, which may be of recipient or donor origin. Most studies of EBV infection and lymphoproliferation have focused on the pediatric age group. METHODS: We have undertaken a prospective study of EBV infection in adult liver transplant recipients. Sequentially collected peripheral blood lymphocytes were examined with a recently developed quantitative polymerase chain reaction assay. The assay quantitates EBV DNA genomic titre over a 5 log10 range. RESULTS: Compared with healthy EBV seropositive people not undergoing immunosuppressive therapy, blood EBV DNA titre is elevated in patients with liver disease before transplantation. Overall, highest titres were observed during the first posttransplant month, and in the context of antilymphocyte therapy. In one patient, lymphoproliferation was associated with high titres which fell during reduction of immunosuppressive therapy. In another patient with lymphoproliferation of donor lymphocyte origin, blood EBV DNA titre was not as high. CONCLUSIONS: EBV proliferation is seen in the context of advanced liver disease and after liver transplantation. EBV DNA quantitation is a useful tool to examine the effects of immunosuppression on EBV-associated lymphoproliferation, and may be an essential technique for programs exploring the merits of EBV adoptive immunotherapy.

Lamivudine without HBIg for prevention of graft reinfection by hepatitis B: long-term follow-up.

BACKGROUND: This open, multicenter study was conducted to evaluate the efficacy and safety of lamivudine prophylaxis given to chronic hepatitis B virus-(HBV) infected patients before and after orthotopic liver transplantation (OLT). We now present long-term data that follow our previous short-term report. METHODS: Twenty-three patients were treated with lamivudine (100 mg orally, daily); 13 (57%), were serum HBV DNA positive (Abbott Genostics, Abbott Laboratories, Chicago, IL) at study entry. Patients received lamivudine for at least 4 weeks before OLT, and for up to 50 months (median 25 months) after OLT. RESULTS: Of the 23 treated patients, 17 survived to undergo OLT. Eleven patients (65%) survived up to 4 years (median 36 months) after OLT. One of the survivors stopped lamivudine because of a possible adverse reaction 9 months post-OLT, and prophylaxis with HBV immune globulin was then established. Ten survivors continue lamivudine. Eight long-term survivors have normal liver function without evidence of HBV reinfection. Of the 17 transplanted patients, 6 died. Four patients died (3 days to 5 months post-OLT) without evidence of graft reinfection. Two further patients died at 19 and 23 months post-OLT from graft failure. Both patients had YMDD variant detected at 12 months post-OLT. Two other patients with YMDD-variant HBV remain alive on lamivudine, 9 and 15 months after development of the variant. CONCLUSIONS: Lamivudine, given before and after OLT, prevents significant graft reinfection for the majority of treated patients. The study has also shown that lamivudine is extremely well tolerated by liver failure patients and for a prolonged period after transplantation.

Direct visualization and quantitation of cytomegalovirus-specific CD8+ cytotoxic T-lymphocytes in liver transplant patients.

BACKGROUND: CMV infection remains a significant clinical problem in the context of LT. Changes in the magnitude of the CMV-specific CTL response after LT have not previously been assessed but may be important in determining the outcome of CMV infection. METHOD: We used a fluorescent HLA-B*0702-CMV peptide tetrameric complex to directly visualize and quantitate CMV-specific CD8+ CTL both in immunosuppressed patients after LT and in immunocompetent controls. RESULTS: CMV-specific CD8+ CTL, at a frequency ranging from 0.1 to 5.8% of CD8+, were detected in the peripheral blood of 22 of 25 B*0702, CMV immunoglobulin G seropositive individuals, with no difference observed between immunocompetent controls and patients >3 years after LT. In CMV seropositive LT recipients who did not have symptomatic CMV infection during the first 3 months after LT, CMV-specific CD8+ CTL magnitude initially decreased, then increased up to 5 times higher than pre-LT levels within 3 months. Two CMV seronegative recipients of seropositive donors had symptomatic CMV infection in association with high viral load. In both patients, no CD8+ CTL response was detected before the onset of symptoms, and a reduction in viral load was observed during antiviral therapy. However, polymerase chain reaction negativity was achieved only when a demonstrable CMV-specific CD8+ CTL response was generated. Responses were never observed in asymptomatic CMV seronegative patients. CONCLUSIONS: We suggest that the generation of CMV-specific CD8+ CTL may be driven by, and seems to coincide with the suppression of, viral reactivation. Direct monitoring of CMV-specific CD8+ CTL using an HLA-peptide tetramer may prove to be of value in the management of patients after LT.