pDCs express IDO in PBMCs exposed to HIV. PBMCs from HIV-uninfected donors were cultured with microvesicles (control; open bars) or AT-2 HIV (solid bars) for 24 hours, and IDO protein expression was detected by flow cytometry in CD4⁺ T cells (CD3⁺CD4⁺), CD8⁺ T cells (CD3⁺CD4⁺), monocytes (CD4⁺CD3⁻CD8⁻BDCA2⁻), and pDCs (CD4⁺CD123⁺BDCA2⁺). (A) Mean IDO-PE MFI (n = 5) ± SE gated on each cell type is shown. (B) One representative experiment of 5 tested is shown; left panel shows gate on pDCs among CD4⁺ cells; right panel shows histograms for MFI on isotype control (black), and IDO PE on microvesicle-treated (control; green) and AT-2 HIV-treated (red) cells. (C) Intracellular staining for IDO in pDCs enriched by magnetic separation with anti-BDCA4–coated beads and cultured with or without AT-2 HIV.