T-bet levels correlate with intracellular IFN-γ levels in aplastic anemia patients. (A-B) We examined the intracellular IFN-γ levels using flow cytometric analysis in PBMCs from aplastic anemia patients (n = 10) and healthy controls (n = 5). CD4⁺ and CD8⁺ T cells from aplastic anemia patients showed increased intracellular levels of IFN-γ compared with controls. The increased expression of intracellular IFN-γ in aplastic anemia patients correlated with increased T-bet protein levels observed in the same patients. The differences in the percentages of double-positive CD4⁺/IFN-γ⁺ and CD8⁺/IFN-γ⁺ cells between healthy controls and patients examined were significant (P = .025 and P = .035, respectively). (C-D) CD4⁺ and CD8⁺ T cells from aplastic anemia patients showed increased intracellular IFN-γ levels after stimulation for 24 hours with PMA and ionomycin (P+I). The graphs show the percent of CD4⁺/IFN-γ and CD8⁺/IFN-γ cells before (•) and after (▪) stimulation. The differences in stimulated cells were also significant. Horizontal lines represent mean values.