Higher frequencies of PD-1⁺CD4⁺ T cells expressing CTLA-4, LAG-3, or ICOS are found in IRIS patients before ART initiation. The percentage of CTLA-4⁺ (A), LAG-3⁺ (B), and ICOS⁺ (C) cells within PD-1⁺CD4⁺ T lymphocytes in HIV⁺ controls (open symbols), HIV⁺ IRIS patients (black symbols) were measured before ART initiation. The same molecules were measured in healthy donors (gray symbols). Percentage of PD-1⁺Ki67⁺ expression within Treg was also measured (D).