Recent Trends in the Immune Response against Hepatitis C Virus

Abstract

Hepatitis C Virus (HCV) represents a viral pandemic infecting
170 million people worldwide, 80% of whom develop
persistent infection and approximately 20% cirrhosis. HCV
is present in numerous quasispecies in each individual
patient, caused by its very high mutation rate. The development
of quasispecies has, as a consequence, the development
of escape mutants to humoral immunity. Cellular
immunity, on the other hand, is believed to be the immune
systems effector arm that is utilized the most in the fight
against HCV. Recent data suggest that a vigorous, polyclonal
and multispecific proliferative CD4+ T-cell
response, and especially a Th1 shift in the cytokine profile
of peripheral blood is associated with viral clearance. CD4+
Th1 immune responses are needed to prime and maintain
the CD8+ cytotoxic T lymphocytes (CTL) response which
is responsible for eliminating infected cells. Unfortunately,
the response of cytotoxic T lymphocyte in persons with
chronic hepatitis C infection seems to be insufficient to
contain viremia but sufficient to cause collateral damage
through the elaboration of inflammatory cytokines in the
liver. A better understanding of the immunity in conjunction
with the assessment of viral replication may facilitate
further immunotherapeutic and vaccine strategies against
HCV infection.
Key words: CD4, CD8, chronic hepatitis C, HCV (Hepatitis
C Virus), immune response, immunity, cytokines