Hepatitis B virus (HBV)-specific in vitro antibody production by peripheral blood mononuclear cells (PBMC) after vaccination by recombinant hepatitis B surface antigen (rHBsAg).

To study the immunization induced by rHBsAg, we analysed the in vitro antibody production (IVAP) to HBsAg by PBMC from 18 subjects vaccinated by two injections on days 0 and 30. HBsAg-specific IVAP was detectable in all subjects after both the first and the second injection, and lasted for about 10 days and then disappeared. However, when the spontaneous HBsAg-specific IVAP became negative, HBsAg stimulation of PBMC cultures induced again a specific HBsAg IVAP. Cultures of cell populations separated by erythrocyte rosetting or Percoll density centrifugation showed that the cells responsible for spontaneous secretion, after in vivo stimulation, were low-density B lymphocytes. High-density B lymphocytes were involved in anti-HBs production induced by in vitro stimulation when spontaneous secretion disappeared. These data suggest that the IVAP test could be a source of important information along with serologic analysis for exploration of the immune response to hepatitis B vaccine.

Hepatitis C virus (HCV)-specific in vitro antibody secretion by peripheral blood lymphocytes: correlation with progression of disease and HCV RNA in HCV antibody-positive patients.

Hepatitis C virus-specific in vitro antibody production (HCV IVAP) by peripheral blood lymphocytes in 53 HCV antibody-positive patients was investigated in comparison with alanine aminotransferase (ALT) levels and HCV RNA in serum samples. All 29 HCV IVAP-positive patients were HCV RNA positive; 26 had elevated ALT levels. Among the 24 HCV IVAP-negative patients, 16 were HCV RNA negative, with 12 presenting normal ALT values. These data indicate that HCV IVAP results are highly correlated (P < 0.001) with HCV RNA results and ALT levels. Our study indicates that HCV IVAP can be used as a novel assay in the diagnosis and pathogenesis exploration of HCV infection.