pDCs accumulate in secondary lymphoid tissues after infection with influenza virus via 2 different routes. (A) C57Bl/6 mice were either mock-infected (PBS) or infected with influenza virus intraperitoneally. After 18 hours, peripheral blood and spleens were harvested, stained, and analyzed by flow cytometry. A representative FACS plot for pDC gating is shown here derived from a spleen from a resting mouse. (B) C57BL/6 mice were either mock-infected or infected with influenza virus by intranasal instillation. After 8 or 18 hours, MLNs were analyzed by flow cytometry. Each group contained 5 mice, and the experiment was performed 3 times with similar results. Lymphocyte and pDC numbers in mediastinal nodes are shown here as the mean ± SEM of 5 animals. *P < .05; **P < .005