Objectives: To investigate the relationship between pre-treatment levels of anti-hepatitis C virus (HCV) immunoglobulin M (IgM) antibodies and the outcome of interferon therapy, and also the relationship with genotypes and quantitative viraemia.
Patients: One hundred and four patients with biopsy-proven chronic hepatitis C without cirrhosis, consecutively enrolled in three general hospitals in Turin, Italy, and treated according to the same interferon schedule (3 MU of recombinant alpha-2b interferon three times a week for 6 months). Anti-HCV IgM were measured by a second-generation enzyme-linked immunoassay and results expressed as sample-cutoff ratio. In 30 patients, determination of viraemia by branched DNA (bDNA) and genotyping were performed and the correlation with anti-HCV IgM ratios was assessed.
Results: According to univariate analysis, anti-HCV IgM ratios, age, serum gamma-glutamyltranspeptidase (gamma-GT) and ferritin levels were significantly associated with sustained response to therapy. A log-linear model, testing the effect of these variables on response to therapy, showed that anti-HCV IgM ratio was the only independently associated variable (P=0.00057). Anti-HCV IgM were associated with viraemia levels (r=0.57), but not with genotype distribution. Patients with anti-HCV IgM ratio less than 1 were sustained responders to the 'standard therapy' in 65% of cases. By contrast, among patients with a ratio greater than 3, sustained response was achieved in only one patient (3%), while 73% were non-responders; the majority of relapsers were found among patients with a ratio between 1 and 3.
Conclusion: Anti-HCV IgM antibodies provide an easily accessible and cheap serological marker of active viral replication, and are significantly related to the outcome of interferon therapy in patients with chronic hepatitis C.