PROMINENT PROLIFERATIVE RESPONSE OF PERIPHERAL-BLOOD MONONUCLEAR-CELLS TO A RECOMBINANT NONSTRUCTURAL (NS3) PROTEIN OF HEPATITIS-C VIRUS INPATIENTS WITH CHRONIC HEPATITIS-C

The proliferative response of peripheral blood mononuclear cells (PBMC ) to a recombinant nonstructural (NS3) protein of hepatitis C virus (H CV) was studied in 41 patients with chronic hepatitis C. Of them, 28 h ad chronic persistent hepatitis (CPH) and 13 chronic active hepatitis (CAH). The positive proliferation rate of PBMC to the recombinant NS3 protein, T9Ag, was 66% in the 41 patients (77% in CAH versus 61% in CP H; P > 0.05) when stimulation index (SI) = 4 was set as the cut-off va lue. However, mean SI of CAH patients was significantly higher than th at of CPH patients (8.3+/-5.2 versus 5.1+/-3.6; P < 0.05). Six other c hronic hepatitis patients who were repeatedly negative for anti-HCV an tibody but positive for serum HCV RNA also had an SI of greater than o r equal to 4.0. The frequency of cellular immune response to the T9Ag is among the highest results obtained by using HCV antigens tested so far. Our studies thus indicate that NS3 is an immunologically importan t region of HCV for T cells. Moreover, the proliferative response to T 9Ag may help to establish hepatitis C etiology in chronic hepatitis pa tients who are seronegative with currently available anti-HCV assays.