Migration of PBMCs toward supernatants of blood DC subsets exposed to influenza virus. Purified blood DCs from 4 donors were exposed to influenza virus for 24 hours and supernatants were used in a migration assay. Supernatant (30 μL) was added to the lower part of a migration chamber and 7.5 × 10⁵ PBMCs were added on top of a 3-μm–diameter pore filter. After a 45-minute incubation at 37°C, with 5% CO₂, migrating cells were harvested, counted, and stained for flow cytometry. Migration of each cell subset in the different conditions is expressed as absolute cell number ×10³ in the lower well after a 45-minute incubation. Paired t test. Blue bars indicate medium + virus; red, pDC SN; and green, mDC SN. (A) Total cell counts by trypan blue exclusion. (B-D) Counts of CD14⁺ monocytes (B); CD16⁺CD56⁺ NK cells (C); and CD4⁺ effector memory T cells (D). BC = buffy coat.