Detection and persistence of specific iga antibodies in serum of patients with hepatitis A by capture radioimmunoassay

The serum immunoglobulin A (IgA) response to hepatitis A virus (HAV) was investigated with a sensitive capture radioimmunoassay. In serial serum samples drawn from 15 patients with viral hepatitis A, IgA anti‐HAV antibodies reached their highest titer between 1–2 weeks after onset and peak titers ranged from 10,000–20,000. Serum samples were available from six patients 30–32 months after onset of illness. These samples were all positive for IgA anti‐HAV and some had titers similar to peak titers during illness. However, the height of the titration curves, expressed as the binding ratio (BR) at a dilution of 1/1000, was in all cases significantly lower at 30–32 months than during acute illness and early convalescence. The significance of the persistence of the IgA anti‐HAV and possible reasons for the change in the BR are discussed.