Hu-NSG mice were each bitten on their rear footpads by approximately four mosquitoes. Unbitten mice were used as controls. At 12, 24, or 48 hours post-bite, mice were euthanized and the indicated tissues were collected. Human leukocyte populations were assessed via flow cytometry. Graphs show the mean frequency of immune cell populations (with outliers removed) as a percentage of human CD45+ cells in bitten (n = 6, 12 or 48 hours post-bite; n = 5, 24 hours post-bite) or control mice (n = 4, 12 or 48 hours post-bite; n = 5, 24 hours post-bite). Error bars represent 1 SEM. T-tests were performed using Graphpad Prism. Multiple comparisons were corrected for using the Holm-Sidak method, which increased the significance threshold to p < 0.01. #, p<0.1; ##, p<0.05; *, p<0.01; **p<0.005. Abbreviations: DC = Dendritic Cell; MΦ = Macrophage; NK = Natural Killer. Cell Markers used to define cell populations: Myeloid Cells, CD45+CD3-CD11c+; Activated Myeloid Cells, CD45+CD3-CD11c+HLADR+; Monocytes, CD45+,CD3-,CD11c+,CD11b+; B Cells, CD45+CD3-CD19+; NK Cells, CD45+CD3-CD56+; Activated NK Cells, CD45+CD3-CD56+CD69+; Proliferating NK Cells, CD45+CD3-CD56+Ki67+; Monocytes/MΦs, CD45+CD3-CD14+.