Synthesis of antibodies to hepatitis B virus by cultured lymphocytes from chronic hepatitis B surface antigen carriers

Abstract

It has been postulated that host immune defects are responsible for the development and persistence of the hepatitis B surface antigen (HBsAg) carrier state. The nature of these defects is unknown, but the absence of a readily detectable antibody response to HBsAg (anti-HBs) may be important. The synthesis of both anti-HBs and antibody to hepatitis B core antigen (anti-HBc) in cultures containing peripheral blood mononuclear cells from chronic HBsAg carriers and from control (antibody-positive) patients was measured in the presence of pokeweed mitogen. Similar amounts of polyclonal IgG and IgM were synthesized by cultures containing lymphocytes from chronic carriers and controls. Anti-HBc was detectable in lymphocyte supernatants from 2 of 20 controls and from 21 of 29 carriers. The presence of anti-HBc synthesis in vitro correlated with high serum titers of anti-HBc. In contrast, anti-HBs was detected in lymphocyte supernatants from 6 of 20 controls (predominantly in those who had high serum titers of anti-HBs) but in none of the supernatants from 29 HBsAg carriers. In order to identify the mechanisms for the lack of detectable anti-HBs synthesis by chronic HBsAg carrier lymphocytes, co-culture experiments were performed using T and B lymphocyte fractions that had been purified by affinity chromatography. B lymphocytes from carriers co-cultured with allogeneic irradiated ("helper") T lymphocytes from controls synthesized normal amounts of IgG, IgM, and anti-HBc but still did not synthesize detectable amounts of anti-HBs. In the converse experiments, B lymphocytes from controls were co-cultured with irradiated T lymphocytes from carriers. The T lymphocytes from 16 of 24 carriers augmented anti-HBs production by control B cells normally, the remaining eight did not. Finally, mixtures of control B cells and control irradiated T lymphocytes were co-cultured with T lymphocytes from chronic HBsAg carriers. 5 of 12 carriers demonstrated active suppression of anti-HBs production, and in three this suppression was specific, as IgG and IgM production remained normal. We conclude that chronic HBsAg carriers have a specific B lymphocyte defect in anti-HBs production. In addition, defects in the function of regulatory T lymphocytes may contribute to the absence of anti-HBs synthesis in some HBsAg carriers.