The percentages of Treg (CD25+ Foxp3+/CD4) and TFH reg (CXCR5+ Foxp3+/CD4) within the CD4+ T lymphocyte region were similar in both CVID groups and in N (mean ± SD, Group I, Treg: 4.42 ± 1.61%, TFH reg: 3.54 ± 1.38%; Group II, Treg: 4.88 ± 4.61%, TFH reg: 3.21 ± 2.87%; N, Treg: 4.00 ± 2.16%, TFH reg: 2.30 ± 1.83%). Here, CXCR5 is linked to common variable immunodeficiency.