Reduced CTLA-4 expression in memory Tregs in individuals with CTLA-4 mutations. (A) Expression of Foxp3 and total CTLA-4 in unstimulated CD4 T cells. CTLA-4 MFI (large font) is shown for the total Foxp3⁺ and Foxp3⁻ populations. Percentage values are shown in quadrants. (B) Comparison of percentage of memory CD4 T cells (CD45RA⁻) in Foxp3⁺ (Treg) and Foxp3⁻ (Tcon) compartments in CTLA-4–deficient individuals (n = 14) and controls (n = 22). (C) Representative expression of Foxp3 and total CTLA-4 in unstimulated CD4 T cells gated on CD45RA⁺ naive (top) or CD45RA⁻ memory subsets (bottom). CTLA-4 MFI (large font) is shown for total Foxp3⁺ cells and Foxp3⁻ cells. Percentages are shown in quadrants. (D) Relative CTLA-4 expression in healthy controls (n = 33) and individuals with CTLA-4 heterozygous mutations (n = 14). Relative expression is calculated as the fold CTLA-4 MFI change between of nTcons and mTregs. (E) Foxp3⁺ Treg percentage in unstimulated CD4 T cells comparing CTLA-4 mutation carriers and controls.