Figure 1.

Expression of NK-cell surface receptors on mononuclear cells isolated from peripheral blood (PB) and synovial fluid (SF) of patients with chronic arthritis. The cells were stained for CD3, CD56 and a panel of NK-cell-associated receptors. NK cells were defined by gating for CD3^– CD56⁺ lymphocytes. (a) Expression profile of CD94/NKG2A, defined by staining with monoclonal antibodies as well as by tetramers of HLA-E in complex with the B7 leader encoded peptide. The data show one representative patient, with SF drawn from both knees denoted SF_r for right knee and SF_l for left knee. (b) Frequency of CD56^bright and CD94^bright NK cells (24 patients and eight healthy controls). (c) Frequency of NK cells expressing different KIR molecules and LIR-1 (Patient PB: n = 15 for KIR stainings and n = 12 for LIR-1, SF: n = 17 for KIR and n = 13 for LIR-1). For paired comparison between PB and SF NK cells: KIR3DL1 P < 0·001; KIR2DL2 P < 0·001; KIR3DL2 P < 0·001; LIR-1 P = 0·002).