Hepatitis C virus (HCV) specific immune responses in anti-HCV positive patients without hepatitis C viraemia

摘要

BACKGROUND/AIMS—Mostpatients infected with hepatitis C virus (HCV) develop chronicinfection and persistent viraemia. The immune mechanisms responsiblefor resolution of viraemia remain poorly understood. HCV specifichumoral and cellular immune responses in patients with and withoutviraemia were investigated. 
METHODS—In vitro Thelper (TH) lymphocyte responses to structural andnon-structural HCV proteins were determined by means of proliferativeresponse and cytokine production in 35 anti-HCV positive/HCV RNAnegative patients and in 31 patients with chronic HCV infection andpersistent viraemia. Humoral responses were determined by measuring HCVspecific antibody quantity and specificity. 
RESULTS—ATH response to two or more HCV proteins was present in 18 of 35 patients with serological viral clearance compared with just oneof 31 viraemic patients (p = 0.00001). HCV specific interferon-γproduction was increased only in the former group. In contrast, theantibody levels were significantly lower and directed at fewer HCVantigens in patients with undetectable HCV RNA. 
CONCLUSIONS—Patientswithout viraemia after HCV infection frequently have strongTH lymphocyte responses of the TH1 type tomultiple HCV antigens many years after the onset of infection, whereasantibody responses are less marked. These results suggest that controlof HCV replication may depend on effective TH lymphocyte activation.