SERUM IGM ANTIBODIES TO HEPATITIS-C VIRUS IN ACUTE AND CHRONIC HEPATITIS-C

A standardized commercially available immunoassay is not available for detection of IgM antibodies against hepatitis C virus antigens (IgM a nti-HCV). Therefore, different ''in-house'' enzyme immunoassays have b een assessed. These assays vary greatly in sensitivity, but specificit y seems satisfactory in all of them. A typical IgM antibody response t o HCV antigens is usually found in nearly all patients with acute hepa titis C. This antibody response rarely precedes the appearance of IgG anti-HCV, and it persists for a few months at high titer. Low titers o f IgM anti-HCV are detectable in 50-80% of cases with chronic hepatiti s C. IgM anti-HCV reactivity is typically found during acute exacerbat ion of chronic hepatitis C. Furthermore, many patients with chronic ac tive hepatitis C without acute exacerbation also have IgM anti-HCV. In these patients a correlation exists between the titer of IgM anti-HCV and the biochemical parameters of liver disease. When alpha interfero n therapy induces a sustained remission of liver disease activity, pos itivity for IgM anti-HCV disappears in more than 70% of cases. In cont rast, patients who do not respond to therapy rarely loose IgM anti-HCV . In conclusion, serum IgM antibodies to HCV antigens are reliable mar kers of active HCV-induced liver disease both in acute and in chronic HCV infection.