A. Left hand panel. IL-2 secretion by KIR3DL2CD3ε jurkat reporter cells stimulated with 221B27, 221, 221B7, 221A3 and 221G transfectants in the presence of isotype control IgG2a or HC10 MAbs as indicated. Right hand panel. IL-2 secretion by KIR3DL2CD3ε jurkat reporter cells stimulated with B27+ and B27-EBV-transformed B cell lines in the presence of the indicated antibodies. B Left hand panel. IL-2 secretion by KIR3DL2CD3ε jurkat reporter cells stimulated with class I transfected 221 cells without (hatched bars) or with (open bars) acid treatment. Right hand panel. IL-2 secretion by KIR3DL2CD3ε jurkat reporter cells stimulated with B27+ and B27-EBV-transformed B cell lines without (hatched bars) or with (open bars) acid treatment. Data in A and B are representative data from 1 of 3 independent experiments: mean values +/- 1SD. C. Left hand panel. IFNγsecretion by KIR3DL2+NK cells stimulated with parental 221 cells or 221-B27, -B7, -B35, - A3 or -G cells. Mean values+/- 1SEM from three independent experiments with two NK cell lines. D. Effect of anti-KIR3DL2 MAbs DX31 and heavy chain antibodies (HC10) or isotype (IgG2a) on IFNγsecretion by KIR3DL2+NK cells stimulated with 221B7 or 221B27 cells. Mean values+/- 1SEM from three independent experiments with two NK cell lines. E. Representative FACS staining of CD107a expression by KIR3DL2+NK cells stimulated with 221B27 or 221B7 cells with anti-KIR3DL2 (DX31), heavy chain (HC10) or isotype (IgG2a) MAbs. F. Upper panel. Mean values for CD107a expression by KIR3DL2+NK cells stimulated with 221 or HLA-B27, -A3, -B7, -B35 or HLA-G expressing 221. Centre and lower panel. Mean values for CD107a expression by KIR3DL2+NK cells stimulated with 221B27 or 221B7 cells with anti-KIR3DL2 (DX31), heavy chain (HC10) or isotype control (IgG2a) MAbs. Mean values +/- 1SEM from four independent experiments with 2 different NK cell lines. Hatched bars indicate CD107a expression by NK cells stimulated with untreated cells and unfilled bars indicate CD107a expression by NK cells stimulated with acid-treated 221 cells. G Upper panel. Proportions of viable CFSE-labelled Dead stain low (lower gate) 221 transfectants after 6 hours incubation with/without KIR3DL2+NK cells. Centre and lower panel. Proportions of viable CFSE-labelled 221B27 cells after coculture with KIR3DL2+NK cells with HLA-class I heavy chain (HC10), KIR3DL2 (DX31) or isotype (IgG2a) MAbs. H. Upper panel. Mean proportions of viable CFSE+ 221B27, 221 cells or 221 cells transfected with other HLA-class I after incubation with KIR3DL2+NK cell lines. Centre and lower panels. Effect of the anti-KIR3DL2 (DX31) and heavy chain antibodies (HC10) on the proportions of viable CFSE-labelled 221B27,221B7 or 221G cells incubated with KIR3DL2+NK cells. Mean values +/-1SEM from three experiments with 2 different NK cell lines. *,** and *** p<0.05, 0.01 and 0.005 by ANOVA (paired measures test).