The interaction of non-cythopatic, hepatotropic viruses of hepatitis B and C with the host’s immune system plays
a critical role in determining the viral clearance and it contributes to the liver damage. The initial line of defence is
antigen non-specific and is mediated by natural killer cells and macrophages. Simultaneously, virus-specific
immunity is induced by professional antigen presenting cells that process and present viral antigens to T and B
lymphocytes in the regional lymph nodes. Thereafter, viral specific T helper cells are activated and these cells initiate
the anti-viral immune responses of B and CTL lymphocytes. Early, multispecific T cell responses are associated
with viral clearance, whereas the imbalance of viral specific Th1 and Th2 lymphocytes plays a crucial role in the
viral persistence. The imbalance of viral specific Th1 and Th2 lymphocytes leads to inadequate activation of antigen
specific CTL cells. After recognition of viral antigens, T helper lymphocytes are differentiated to Th1 and Th2 cells
according to the type of secreted cytokines. Th1 cells produce cytokines: interleukin-2, IFN-γ, TNF-α, which are
responsible for effective activation of CTL cells. In contrast, interleukin-4, interleukin-5 and interleukin-10 are
secreted by Th2 cells, which are involved in activation of B lymphocytes and in production of neutralizing antibodies.
These finding suggests that the viral clearance is associated with the early development and adequate mounting of
the anti-viral multispecific immune responses of T helper and cytotoxic T lymphocytes.
immunopathology, hepatitis B, hepatitis C, immune response, viral clearance.