Diagnostic Value of Immunoglobulin A and M antibodies as a disease Marker for hepatitis A Infection

This study was conducted to assess the effect of anti-immunoglobulin antibodies on the measurement of the humoral immune response in hepatitis A virus (HAV) infected patients. Serum samples from 47 patients with acute hepatitis A and from 47 age/sex matched healthy adult subjects were tested for IgA, IgG and IgM by ELISA. Antiimmunoglobulin antibodies were defined using goat immunoglobulins as a target to characterize distinct changes in levels of interacting immunoglobulins. Initial results obtained before removal of antibodies that interacted with goat immunoglobulins suggested that HAV patients had increased levels of IgA and IgM in their sera. It was found that normal individuals had mean IgA, IgG and IgM levels of 2.52 ± 0.22 mg/ml, 9.86 ± 0.94 mg/ml and 1.75 ± 0.13 mg/ml, respectively while HAV patients had mean levels of 2.89 ± 0.20 mg/ml, 10.03 ± 1.05 mg/ml and 1.97 ± 0.13 mg/ml (p <0.0002, p <0.41 and p <0.0001). However, the mean levels of IgA and IgM in HAV infected sera, after purification from antibodies that interacted with goat immunoglobulins, were 2.49 ± 0.21 mg/ml and 1.73 ± 0.14 mg/ml. Therefore, there was no significant difference in HAV patients compared to normal individuals (p <0.55 and p <0.56). The presence of circulating immune complex in serum during the early phase of infection may contribute to immunopathological effects in the infected host and provide some new insights into antibody response to HAV.