Cross-linking of hOSCAR triggers calcium flux mobilization in myeloid cells. Human serum–saturated monocytes (A) or mono-DCs (B) were loaded with Indo-1 am, and the rise in intracellular Ca²⁺ was analyzed on FACStar^Plus flow cytometer, by recording in real-time the 405/530-nm fluorescence ratio. Monocytes were incubated (arrowhead) at 37° C with anti-CD44 and anti-CD89 mAbs, as negative and positive controls, respectively. Mono-DCs were incubated (arrowhead) at 37° C with anti–HLA-A, -B, -C mAbs and recombinant human MIPα, as negative and positive controls, respectively. The 405/530-nm ratio was recorded during the primary mAb binding. At set time points (arrow) goat F(ab′)₂ anti-mouse was added to allow receptor cross-linking. Data shown are representative of 3 experiments. (C) Ligation of hOSCAR induces secretion of IL-8 and IL-12p40 by mono-DCs. Immature mono-DCs were stimulated by coated mAbs or LPS, as described in “Materials and methods.” After 24 hours, the levels of secreted IL-8 and IL-12p40 were tested by ELISA. Data shown are representative of 3 experiments and display the mean and standard deviation of 3 independent samples.