Fig. 1.

A comparison of CD3^-CD56⁺ natural killer (NK) cells between hepatitis C virus (HCV)-infected individuals (squares) with healthy individuals (triangles) as determined by flow cytometry. (a) Strategy for the six-colour flow cytometry, gating on CD56^dim, CD3^- NK cells to determine killer-cell immunoglobulin-like receptors (KIR) (CD158a,h, CD158b,j and CD158e) and NKG2A expression. Shown are three dot plots demonstrating the expression of CD158e and NKG2A on CD158a,h^-,CD158b,j^-, CD3^-CD56^dim NK cells. (b) Percentage of CD56^dim and CD56^bright NK cells as a fraction of the total lymphocyte population. The CD56^dim NK cells are recorded on the left axis (closed symbols) and CD56^bright NK cells on the right axis (open symbols). (c) Frequencies of NK cells expressing individual major histocompatibility complex (MHC) class I receptors as determined by anti-CD158a,h (KIR2DL1/2DS1), anti-CD158b,j (KIR2DL2/2DL3/2DS2), anti-CD158e (KIR3DL1) and Z199 (NKG2A). The data shown are the percentage of total CD56^dim NK cells expressing the indicated receptor. (d) Comparison of the overall frequencies of NK cells expressing receptors for which they have an MHC class I ligand (an HLA-B or HLA-C allele for the KIR, or HLA-E for NKG2A). (e) Frequencies of NK cells expressing a cognate HLA-C receptor in individuals with and without an HLA-C group 1 allele. Comparisons between the healthy donors and HCV infected individuals were performed using the Mann–Whitney U-test. P-values of 0·05 or less are indicated.