Increased AICD but not TRAIL-R–mediated-apoptosis of XIAP^G466X-expressing T lymphocytes. (A) TRAIL-R–mediated apoptosis of T-cell blasts from healthy controls (Ctr.), patients expressing null mutations of XIAP (XIAP−), patients III-1 and III-2 expressing both XIAP^G466X and CD40L^G219R, and a female (II-1) heterozygous carrier of both XIAP^G466X and CD40L^G219R. Cells were stimulated with trimeric TRAIL. One experiment that is representative of 3 independent experiments is shown. (B) AICD of T-cell blasts expressing both XIAP^G466X and CD40L^G219R (patients III-1, III-2, and II-7), XIAP^G466X alone (individual II-5), or CD40L^G219R alone (individual IV) compared with that of cells from 4 healthy donors (Ctr.) and 2 XIAP-null patients (XIAP−). The graph was compiled from 7 independent experiments performed in duplicate. Each point represents the mean of duplicates in which the raw values differed by < 5%. Cells were stimulated with an anti-CD3 antibody. Bars correspond to mean values of each group. **P < .001 and ***P < .0001.