Blood MAIT cells are modified by G-CSF mobilization. (A) Plasma IL-17A levels before and after G-CSF administration (n = 17 donors). (B-C) Frequency and representative FACS plots of Th17 (CD3⁺CD8^negIL-17A⁺), Th1 (CD3⁺CD8^negIFN-γ⁺), Tc17 (CD3⁺CD8⁺IL-17A⁺), and Tc1 (CD3⁺CD8⁺IFN-γ⁺) subsets in PBMCs (n = 15 donors). (D) Number of CD3⁺ T cells per milliliter PB (n = 20 donors); ***P = .0007. (E) Number of Th17 (CD3⁺CD8^negIL-17A⁺), Th1 (CD3⁺CD8^negIFN-γ⁺), Tc17 (CD3⁺CD8⁺IL-17A⁺), and Tc1 (CD3⁺CD8⁺IFN-γ⁺) subsets per milliliter PB (n = 15 donors); **P = .0079, Tc17 number before vs after G-CSF. Data were analyzed using the paired Wilcoxon signed rank test and are presented using box-and-whisker plots showing the median with 25th percentiles (whiskers represent minimum to maximum values). (F) Representative FACS plots depicting IFN-γ and IL-17 expression in sorted donor MAIT, CD4T_con, and CD8T_con populations stimulated ex vivo with phorbol 12-myristate 13-acetate/ionomycin. (G) Frequency of IFN-γ–, IFN-γ/IL-17A–, and total IL-17A–expressing MAIT, CD4T_con, and CD8T_con populations (n = 5-8 donors); **P=.004, frequency of IFN-γ/IL-17A–expressing MAIT cells before vs after G-CSF; *P=.03, frequency of total IL-17A–expressing MAIT cells before vs after G-CSF. (H) Representative FACS plots showing Tbet and RORγt expression by donor MAIT, CD4T_con, and CD8T_con populations in unfractionated PBMCs. (I) Frequency of RORγt-expressing MAIT, CD4T_con, and CD8T_con populations (n = 17 donors); *P = 0.04. (J) Geometric MFI of RORγt expression in donor MAIT cells; **P = 0.006. Data are presented as mean ± standard error of the mean.