Estimation of IgG subclasses of anti-HCV (C100-3) in non-A, non-B fulminant, acute and chronic hepatitis and it's significance.

To determine whether identification of subclasses of anti-HCV IgG would help distinguish between acute and fulminant hepatitis, we assayed serum IgG subclasses of anti-HCV (C100-3) in non-A, non-B hepatitis. Anti-HCV IgG was restricted to two subclasses in different diagnostic conditions; anti-HCV IgG1 and anti-HCV IgG3. Anti-HCV IgG1 was the main subclass in acute hepatitis (AH), and was positive in all the cases and only one case was positive for anti-HCV IgG3. Anti-HCV IgG3 was the dominant subclass in fulminant hepatitis (FH). Out of the total 12 cases of FH, who were positive for either anti-HCV IgG or for any of it's subclasses, in 10 cases (83%), anti-HCV IgG3 had higher optical density (OD) values than anti-HCV IgG1 and in 6 cases (50%) was the only subclass of anti-HCV IgG being positive. In 5 cases with FH, anti-HCV IgG3 became positive even when anti-HCV IgG was negative. These findings from the basis of a new observation and are likely to be helpful in the diagnosis of non-A, non-B fulminant hepatitis.