Decreased NK cell frequency in chronic hepatitis C does not affectex vivo cytolytic killing

Abstract

Prior studies have suggested that natural killer (NK) cell function might be impaired in chronic hepatitis C virus (HCV) infection. Circulating NK cell frequency and cytolytic activity were examined freshly ex vivo in HCV‐infected and uninfected subjects. Surprisingly, the intrinsic cytolytic activity of peripheral blood NK‐enriched cells was similar between HCV‐infected and uninfected groups (P = .91). Although the percentage of circulating CD3⁻CD16/56⁺NK cells was 30% lower in HCV‐infected compared with uninfected subjects (P = .02) paralleled by a decrease of CD56^dim cytolytic NK cells (P = .02), overall K562 cytolysis by unfractionated peripheral blood mononuclear cells was not affected (P = .29). Analysis of the relationships between NK cytolytic activity and other clinical information revealed an inverse association with liver fibrosis stage (P = .035). In conclusion, NK cell cytolytic function does not appear to be impaired in chronic hepatitis C, but higher levels of NK cell cytolysis are associated with less liver fibrosis. (HEPATOLOGY 2006;43:573–580.)