Increased frequencies of Th17 cells in the BM of aplastic patients (AA) at diagnosis. BM from 2 patients (1 moderate and 1 severe AA) and 1 healthy control were stained with 4,6-diamidino-2-phenylindole and anti-IL-17 and then analyzed using confocal microscopy. BMMCs from healthy controls (n = 4) and AA patients at diagnosis (n = 7) were stained with anti-CD3 and anti-CD8 antibodies followed by intracellular staining with anti-IL-17 antibody. Cells were analyzed by flow cytometry after stimulation for 6 hours with PMA and ionomycin in the presence of monensin. (A) Representative confocal analysis of the BM from healthy control (top panel) and AA patient (bottom panel). (B) Representative flow cytometric analysis of IL-17 expressions in CD8⁻ T-cell subsets (Th17 cells) in healthy control (left panel) as well as in AA at diagnosis (right panel). The mean value of each group is indicated. (C) Frequencies of Th17 cells in healthy controls (●, n = 4) and in AA at diagnosis (▵, n = 7). The mean value of each group is represented (solid line). (D) Correlation between the frequencies of PBMC and BMMC Th17 cells in AA at diagnosis (n = 7). Normal donors (4 healthy controls) are represented by a dashed line.