Functional T cell assays in patients with heterozygous ITPR3 variants. (A and B) Graphs showing the percentage of (A) CD25⁺ cells within CD4⁺ T cells and (B) CD40L⁺ cells within activated CD25⁺ CD4⁺ T cells after stimulation with PHA in patients (P2: three replicates; P4: two replicates) versus HDs, across three independent experiments; **P < 0.01, two-tailed t test. (C and D) Graphs showing interferon γ (IFNγ), tumor necrosis factor α (TNFα), and interleukin (IL)-2 production in patients (P2, P4, and P5) versus HD T cells after stimulation with (C) anti-CD3/28 and (D) PMA/Ionomycin. Results are expressed as a percentage of cytokine⁺ cells within CD4⁺ and CD8⁺ T cells after excluding naïve cells. (E) Degranulation capacity of CD8⁺ T cells after stimulation with anti-CD3/CD28. Results are expressed as a percentage of CD107a⁺ cells within total CD8⁺ T cells, across three independent experiments, two-tailed t test.