Cell-mediated immunity to hepatitis B surface antigen in man.

Area of Science:

• Immunology
• Hepatology
• Vaccinology

Background:

• Cell-mediated immunity is crucial for viral clearance and pathogenesis.
• The role of cell-mediated immunity to hepatitis B surface antigen (HBsAg) in hepatitis B virus (HBV) infection and vaccination is not fully understood.

Purpose of the Study:

• To investigate delayed hypersensitivity skin test reactivity and in vitro lymphocyte responses to HBsAg in individuals with varying HBV infection and vaccination statuses.
• To assess the role of cell-mediated immunity to HBsAg in the immunopathogenesis of acute and chronic type B hepatitis.

Main Methods:

• An aqueous hepatitis B virus (HBV) vaccine was used as an intradermal skin test antigen.
• Thirty-five individuals were tested: 10 seronegative, 10 HBsAg-positive (chronic carriers), and 15 anti-HBs-positive (5 vaccinated).
• Lymphocyte blastogenic responses to phytohaemagglutinin, concanavalin A, pokeweed mitogen, and purified HBsAg were assessed in vitro.

Main Results:

• Only one vaccinated individual with high anti-HBs titers showed a positive delayed skin test reaction to HBsAg.
• No subject exhibited a positive in vitro lymphocyte blastogenic response to HBsAg.
• Cell-mediated immune responses to HBsAg were not detected after natural HBV infection.

Conclusions:

• Delayed hypersensitivity skin test reactivity to HBsAg is rare, even in hyperimmunized individuals.
• In vitro assays failed to demonstrate cellular immunity to HBsAg, even in hyperimmunized persons.
• These studies provide no evidence that cell-mediated immunity to HBsAg is involved in the immunopathogenesis of acute or chronic type B hepatitis.