Fig. 4.

Intermediate KIR-binding or HLA-A2 binding peptides do not antagonize inhibition by a strong KIR-binding peptide. T2 cells were incubated with VAP-FA, VAP-RA, or VAP-DA alone or in combination and degranulation assays performed. Flow cytometry plots (A) and the results of peptide mix titrations (B) are shown. Peptide mixes were made to 10 μM final concentration. For the titration of VAP-FA and the VAP-FA:VAP-RA combination, the concentration of VAP-FA is plotted, and for VAP-RA and VAP-RA:VAP-DA, that of VAP-RA is plotted. The dashed line indicates the concentration of VAP-FA at which 50% of NK cells relative to VAP-DA alone are inhibited for the VAP-FA:VAP-RA mix. The arrow indicates the 50:50 peptide mix point. (C and D) T2 cells were incubated with VAP-FA or an HLA-A*0201-binding peptide (GILG). (C) Degranulation of CD3⁻CD56⁺CD158b⁺ NK cells in response to T2 cells alone or incubated with the indicated peptides. (D) The fraction of degranulating CD3⁻CD56⁺CD158b⁺ NK cells in response to T2 cells incubated with VAP-FA alone or in combination with GILG or VAP-DA to a final concentration of 10 μM. The dashed line indicates the concentration of VAP-FA at which 50% of NK cells relative to VAP-DA alone are inhibited for the VAP-FA:VAP-DA mix. The arrow indicates the 50:50 peptide mix point. For all experiments, data are normalized to the degranulation observed in response to T2 cells incubated with 10 μM VAP-DA, and the means ± SEM of three independent experiments are shown.