Although patients with APDS and Pik3cdE1020K/+ mice exhibit reduced naive T cells (Figure S1D; Angulo et al., 2013; Avery et al., 2018; Lucas et al., 2014; Preite et al., 2018; Stark et al., 2018), enhanced cell death was also observed in sorted naive (CD62L+CD44lo) Pik3cdE1020K/+ CD8+ T cells post-stimulation (Figure 1B). Here, SELL is linked to activated PI3K-delta syndrome.