Duration and specificity of antibodies to hepatitis C virus in chronic active hepatitis.

To determine the duration and specificity of antibodies to hepatitis C virus in hepatitis B surface antigen-negative chronic active hepatitis, sera from 19 patients seropositive by enzyme immunoassay were assessed by recombinant immunoblot assay. Only 12 of the 19 patients were reactive by immunoblot assay (63%). Patients nonreactive by immunoblot assay had lower signal-cutoff ratios by enzyme immunoassay (1.3 +/- 0.2 vs. 6.5 +/- 0.1; P less than 0.05), higher serum immunoglobulin G levels (4082 +/- 301 vs. 1760 +/- 143 mg/dL; P less than 0.05), and higher serum gamma globulin levels (3.3 +/- 0.5 vs. 2.04 +/- 0.1 g/dL; P less than 0.05) than reactive patients. Twelve of 14 patients with serial studies remained seropositive after 39 +/- 11 months of follow-up (range, 7-113 months). Only patients nonreactive by immunoblot assay became seronegative by enzyme immunoassay during corticosteroid therapy (2/3 vs. 0/6 patients). It is concluded that seropositivity by enzyme immunoassay may not be documented by immunoblot assay. Patients nonreactive by immunoblot assay have lower signal-cutoff ratios and higher gamma globulin levels than reactive patients, and their seropositivity may be nonspecific. Patients nonreactive by immunoblot assay may lose seropositivity by enzyme immunoassay during corticosteroid therapy.