MAIT cells, similar to iNKT cells, are more prone to apoptosis than conventional T cells. (A) Flow cytometry analysis of MAIT cells (CD3⁺TCRVα7.2⁺CD161⁺). MAIT cells from PBMCs of 2 healthy donors (Ctr.) and 2 XIAP patients (XIAP) were detected by staining with anti-TCRVα7.2 and anti-CD161 antibodies and analyzed after gating on CD3⁺ cells. (B) Comparison of numbers of MAIT cells (TCRVα7.2⁺CD161⁺) in CD3⁺ lymphocytes from PBMCs of control healthy donors (Ctr.; n = 15), SAP-deficient patients (SAP; n = 5) and XIAP-deficient patients (XIAP; n = 16). Bars correspond to mean values of each group of cell numbers, unpaired t test (***P < .001). (C) Apoptosis of ex vivo MAIT and Vβ2 T cells from PBMCs of 4 healthy donors (Nos. 4, 6, 9, and 12) after stimulation with anti-CD3 antibody or staurosporine for 8 hours. (D) Apoptosis of cultured MAIT cells stimulated with anti-CD3 or anti-FAS antibodies. Data correspond to 1 experiment in duplicate (error bars correspond to SD) with 2 donors (Nos. 4 and 7). (E) Active caspases were detected by flow cytometry using FLICA in ex vivo MAIT cells from 2 healthy donors (Nos. 4 and 6) after gating on CD3⁺TCRVα7.2⁺CD161⁺. (F) Apoptosis of ex vivo MAIT and iNKT cells from PBMCs of 2 XIAP-deficient patients (P.1 and P.2 in Figure 1B) and from 1 healthy donor (No. 9) stimulated with staurosporine for 8 hours. Data correspond to 1 experiment. (G) Staurosporine induced apoptosis of ex vivo MAIT cells targeted by a control shRNA (sh-control) or a shRNA specific for PLZF (sh-PLZF-1-). Four independent experiments (n = 4) with 2 different donors (Nos. 21 and 22). Mean ± SD; paired, 2-tailed t test (*P < .05).