XIAP-deficiency worsens the proapoptotic phenotype of iNKT cells. (A) Apoptosis of expanded iNKT and Vβ2 T cells from 1 XIAP-deficient patient (P.1 in Figure 1) and 1 healthy donor (No. 16) stimulated with anti-CD3 or anti-FAS antibodies. Data are representative of 1 experiment of 2. Assays were done in duplicate (error bars correspond to SD). (B) GFP (left panels) and XIAP (right panels) expressions in iNKT and Vβ2 T cells from healthy donors infected with a lentiviral pLKO-GFP vector containing either a shRNA for XIAP (sh-XIAP) or scramble shRNA (sh-control), tested at day 4 after infection. Histograms correspond to staining with anti-XIAP antibody or isotype control in GFP-positive (GFP⁺) and GFP-negative (GFP⁻) cells. (C) Apoptosis of GFP⁺ and GFP⁻ iNKT and Vβ2 T cells stimulated with anti-CD3 antibody. Data are mean ± SD of 3 independent experiments with 3 different healthy donors (Nos. 6, 9, and 13) with assays done in duplicate. Paired, 2-tailed t test (**P < .01). (D) Apoptosis of GFP⁺ iNKT and Vβ2 cells stimulated with anti-FAS antibody. Data correspond to 1 experiment representative of 2 with assays done in duplicate (error bars correspond to SD). (E) Same as in panels C and D, except that cells were repeatedly treated with anti-CD3 or anti-FAS antibodies every day and the proportions of GFP⁺iNKT and GFP⁺Vβ2 cells in cultures was determined by flow cytometry. Data represent the loss of GFP⁺ cells targeted with the shRNA for XIAP or the sh-control within the culture compared with the percentage of GFP⁺ cells at day 0. One representative experiment of 2.