Decreased frequencies of Tregs in PB and BM from patients with AA. (A) Representative flow cytometric analysis of Tregs frequencies (gated on lymphocyte population) in (i) AA PB, (ii) AA BM, (iii) control PB, and (iv) control BM. (B) Frequencies of CD4⁺CD25⁺ Tregs in PB and BM of AA patients (n = 9) and healthy controls (n = 4). (C) Reversed ratio of frequencies of CD4⁺CD25⁺ Tregs between BM and PB in AA. Data were expressed as mean ± SEM. *P < .05; **P < .001.