Diagnostic value of anti-hepatitis C virus (HCV) core immunoglobulin M in recurrence of HCV infection after orthotopic liver transplantation

Diagnosis of hepatitis C virus related acute hepatitis by serial determination of IgM anti-HCV titres

BACKGROUND/AIMS

We investigated whether serial determination of IgM to HCV core protein (HCV IgM) may be useful to identify acute hepatitis C (AHC) and to distinguish this disease from reactivation of chronic hepatitis C (r-CHC).

METHODS

We enrolled 35 consecutive patients with AHC identified by seroconversion to anti-HCV and 31 consecutive patients who had been anti-HCV positive for at least six months at the time of reactivation. Titres of HCV IgM were calculated as Index values by a commercially available enzyme immunoassay.

RESULTS

During the early phase of the illness we observed a wide variation in the HCV IgM Index values in all patients in the AHC group and consistent values in all cases in the r-CHC group. The HCV viral load determined soon after the onset of symptoms was of no use in identifying AHC.Twenty-three patients in the AHC group were observed as outpatients for 6-30 months; of these, 10 became plasma HCV-RNA negative within the third month of observation, but three showed a subsequent reactivation of HCV infection.

CONCLUSIONS

Our data indicate that the detection of high and variable titres of HCV IgM in the early phase of the illness may identify acute hepatitis C and allow early antiviral treatment.

Increasing serum levels of IgM anti-HCV are diagnostic of recurrent hepatitis C in liver transplant patients with ALT flares

Recurrent hepatitis and acute rejection share common features which make difficult for diagnosis in liver transplant hepatitis C virus (HCV) positive patients. We studied the usefulness of quantitative monitoring of HCV RNA and immunoglobulin (Ig)M anti-HCV in the differential diagnosis between recurrent hepatitis and acute rejection in 98 consecutive anti-HCV positive liver transplant patients. Aminotransferase levels, serum HCV RNA and IgM anti-HCV were measured at the time of transplantation and monthly thereafter. A liver biopsy (LB) was obtained when serum aminotransferase levels increased to twice or more than normal. During a mean follow-up of 16 months 86 aminotransferase flares were observed. Histology was compatible with recurrent hepatitis C in 44 cases and with acute rejection in 28, doubtful in 14. The fluctuations of HCV RNA serum levels were not significantly different in the three groups. Serum IgM anti-HCV levels increased (from negative to positive or with value variations > or = 0.18) in 36 of 44 cases with recurrent hepatitis C at the time of alanine aminotransferase (ALT) flare. IgM anti-HCV remained unchanged in all rejection cases (P < 0.001), but increased in 10 of 11 histologically doubtful cases that were diagnosed as hepatitis at the second LB. Increasing serum levels of IgM anti-HCV at the time of ALT flares are significantly associated with recurrent hepatitis C in liver transplant patients. The quantitative monitoring of IgM anti-HCV appears to be an additional diagnostic tool for distinguishing recurrent hepatitis C from acute graft rejection with a 100% specificity; 100% positive predictive value and 88.9% diagnostic accuracy.

Multicentre Italian Study Group (MISG) for the standardisation of hepatitis C virus (HCV) PCR

BACKGROUND

Several studies on standardisation of NAT assays for diagnosis of hepatitis C virus (HCV) infection have been carried out in European countries. In fact the widespreading use of nucleic acid amplification technology (NAT) in diagnostic centres for the evaluation of the HCV infection, requires the application of reference external standards to control laboratory performance; but up to date they are not routinely used.

OBJECTIVES

Fifteen diagnostic centres of major Italian Hospitals participated to a quality control study for the standardisation of polymerase chain reaction (PCR)-based HCV-RNA detection, organised by the Committee for the Study of Biotechnology (CoSBio) of the Italian Society of Clinical Microbiology (AMCLI). All the participant centres (PC) used commercial assays, automated or semi-automated.

STUDY DESIGN

The study was performed in four rounds. Altogether each centre received 14 reference negative and 22 reference positive sera. The range of copies number per ml of the reference positive sera was 10(4)-10(7).

RESULTS AND CONCLUSIONS

Considering the 540 samples tested, 4.54% of false negative (FN) and 4.28% of false positive (FP) results were reported. Thereafter the sensitivity and the specificity were 95.65 and 95.89%, respectively. The errors were distributed among seven out of the 15 PCs. The percentage of FP results was uniformly distributed in each shipment, whereas FN results emerged with the sera at lower HCV genome copies number. The analysis of the data obtained suggests that FP as well as FN results may be attributable to errors or to others problems of laboratories. To improve the performance of Italian, as well as of laboratories throughout the world, the use of external reference standards in multicentre collaborative studies will be required.