Prognostic value of HBsAg/IgM complexes in hepatitis B patients: nature of the proteins involved

Hepatitis B surface antigen (HBsAg)/IgM complexes were measured using a solid phase radioimmunoassay in sera of patients with acute or chronic hepatitis B. These complexes were found in 6 out of 18 patients four weeks after the onset of the disease and only one of them developed chronic hepatitis. HBsAg/IgM complexes correlated with HBsAg, hepatitis B e antigen (HBeAg), and pre-S2 concentration. The precipitation of HBsAg/IgM reactivity by polyethylene-glycol (PEG) and the binding of this activity to the surface of certain uncoated enzyme linked immunosorbent assay (ELISA) plates indicates that HBsAg/IgM positivity may reflect the presence of circulating complexes in serum. HBsAg and pre-S2 were found as components of the complexes but anti-HBs, anti-pre-S2, and polymerized human serum albumin (pHSA) were not. An immune binding between HBsAg and IgM is still questionable. Whatever the nature of the HBsAg/IgM complexes, their detection does not seem to be an earlier indicator of prognosis than HBeAg and/or pre-S2.