Decreased numbers of iNKT cells in PBMCs from XIAP-deficient patients. (A) Comparison of iNKT cell (TCRVα24⁺TCRVβ11⁺) counts within CD3⁺ lymphocytes from blood of control healthy donors (Ctrl.), SAP-deficient patients (SAP) and XIAP-deficient patients (XIAP). iNKT cells were detected by staining with anti-Vα24 and anti-Vβ11 TCR antibodies and analyzed after gating on CD3⁺ cells. All XIAP-patients have been infected by EBV except 2 patients who are indicated by arrows. Bars correspond to mean values of each group of iNKT cell numbers, unpaired t test (*P < .05, ***P < .001). (B) Six XIAP-deficient patients (P.1, P.2, P.3, P.4, P.5, and P.6) were tested 2 or 3 times at 6- to 12-month intervals. Patients were infected by EBV (EBV⁺) except P.1.