Crosslinking of NKp44 on IL-3-cultured IPCs reduces IFN-α responses to CpG. Peripheral blood IPCs were cultured overnight in IL-3 and then transferred to wells containing plate-bound anti-NKp44 antibody, in the presence or absence of CpG as IFN-α-inducing stimulant. After 20 hours, culture supernatants were tested for the presence of IFN-α (A-B), MIP-1α (C), and MIP-1β (D). For IFN-α, 2 representative experiments are shown, which were carried out with whole antibody (A), or with F(ab′)₂ fragments (B) to crosslink NKp44. In some experiments, IPCs were also stimulated on anti-BDCA-2 mAb-coated plates for comparison. ▪ indicate control antibody; ▦, anti-NKp44 mAb; □, anti-BDCA-2 mAb.