Figure 1.

Impaired CD56⁺ natural killer‐mediated antibody‐dependent cellular cytotoxicity (NK‐ADCC) responses in chronic hepatitis C virus (HCV) carriers. (a) Gating strategies for CD16, CD107a, interferon (IFN)‐γ and tumour necrosis factor (TNF)‐α on CD3^–CD56⁺ NK cells stimulated with medium alone (unstimulated), P815 cells (P815), anti‐P815 antibody (anti‐P815), antibody‐coated P815 cells (P815 + antibody) and phorbol myristate acetate (PMA) plus ionomycin. Representative results from one chronic HCV‐infected patient and one healthy individual are shown. (b) Degranulation (CD107a) and cytokine secretion (IFN‐γ and TNF‐α) in CD56⁺ NK cells on unstimulated condition or activated with antibody‐coated P815 cells in 31 chronic HCV‐infected patients and 49 healthy controls. The percentages of single‐, double‐ and triple‐positive CD56⁺ NK cells are shown, and the red bars indicate the median values. Comparisons between groups were performed using the Mann–Whitney U‐test. (c) Secreted cytokines were quantified in NK‐ADCC supernatants by enzyme‐linked immunosorbent assay (ELISA). Purified NK cells from HCV carriers (n = 5) and healthy donors (n = 5) were stimulated with antibody‐coated P815 cells for 24 h, and supernatants were collected to test the levels of granzyme B, IFN‐γ, TNF‐α, transforming growth factor (TGF)‐β and IL‐10 by ELISA. Data are shown as the median cytokine concentration and the interquartile range. Statistical analyses were performed by non‐parametric t‐test. All P‐values are two‐tailed and were considered significant when less than 0·05. [Colour figure can be viewed at wileyonlinelibrary.com].