For this experiment, memory CD4+ T cells from three children with newly diagnosed T1D and three age‐matched healthy controls were briefly stimulated with PMA and ionomycin to enable the detection of cytokine transcripts [26, 27], sorted into PD‐1hi and PD‐1lo fractions, and subsequently pooled at a 1:1 ratio to enrich for the rare PD‐1hi cells for the single‐cell analyses (Figure 2A). Here, CD4 is linked to type 1 diabetes mellitus.