Serum immunoglobulin levels in acute A, B, and non-A, non-B hepatitis.

Immunoglobulin M, G, and A concentrations were determined by radial immunodiffusion in sera collected from 117 patients with acute hepatitis A, hepatitis B, or non-A, non-B hepatitis. Statistically significant differences in IgG and IgM levels were detected between the three groups. In particular, elevated IgG and almost-normal IgM levels were regularly detected in patients with non-A, non-B hepatitis while the opposite pattern was seen in patients with hepatitis A. Calculation of a serum IgG/IgM ratio enabled discrimination between most patients with non-B hepatitis. In 92% of patients with hepatitis A, the ratio was less than 6, whereas 82% of patients with non-A, non-B hepatitis had ratios of greater than 6. The IgG/IgM ratio may be of value in distinguishing between subjects with the two forms of the disease when specific serologic tests are unavailable.