Intrahepatic, nucleocapsid antigen-specific T cells in chronic active hepatitis B

Area of Science:

• Immunology
• Hepatology
• Virology

Background:

• Chronic active hepatitis B involves persistent liver inflammation and injury.
• The role of specific T cell responses in the pathogenesis of chronic hepatitis B remains incompletely understood.
• Hepatitis B core antigen (HBcAg) is a key target in cellular immune responses during hepatitis B virus infection.

Purpose of the Study:

• To establish and characterize Hepatitis B core antigen (HBcAg)-specific T cell lines from patients with chronic active hepatitis B.
• To investigate the functional capabilities of these T cell lines, including helper, suppressor, and cytotoxic activities.
• To determine the phenotype and specificity of T cells involved in the immune response at the site of hepatocellular injury.

Main Methods:

• Isolation of hepatic lymphomononuclear cells from patients with chronic active hepatitis B.
• Establishment of T cell lines specific for recombinant and native HBcAg.
• Phenotypic analysis (CD4+, CD8+) and functional assays (proliferation, help, suppression, cytotoxicity) of T cell lines.
• Assessment of specificity against HBcAg and other antigens (hepatitis B surface antigen, tetanus toxoid).

Main Results:

• Five HBcAg-specific T cell lines were successfully established; no hepatitis B virus envelope antigen-specific lines were generated.
• All established T cell lines comprised a mixture of CD4+ and CD8+ T cells.
• CD4+ T cells provided antigen-specific help for B cell anti-HBc production and CD8+ cell proliferation/suppression.
• CD8+ T cells exhibited suppressor activity against autologous HBcAg-specific CD4+ T cells and HBcAg-stimulated anti-HBc production.
• T cell lines demonstrated lectin-dependent cytotoxicity but lacked natural killer activity.

Conclusions:

• Lesional T cells in chronic active hepatitis B are predominantly HBcAg-specific lymphocytes.
• Both helper (CD4+) and suppressor/cytotoxic (CD8+) T cell subsets are present and functionally competent at the site of liver injury.
• These findings highlight the critical role of HBcAg-specific T cell responses in the immunopathogenesis of chronic hepatitis B.