Frequency of mucosal FOXP3⁺ T_regs in treatment-naive and treated HIV-infected patients, patients with norovirus infection, and in healthy controls. (A) Absolute number of mucosal CD4⁺ T cells per 10 hpf. (B) Absolute number of mucosal FOXP3⁺ T_regs per 10 hpf. (C) Frequency of lamina propria T_regs in relation to lamina propria CD3⁺ T cells and (D) to lamina propria CD4⁺ T cells. The horizontal lines denote the median values of each group. *P < .05, **P < .01, ***P < .001.