PDCD1 and type 1 diabetes mellitus: Of note, the frequencies of CXCR5−PD-1int and CXCR5+PD-1int T cells did not differ between the study groups (ESM Fig. 2), excluding the possibility that the increase in PD-1hi Tph and Tfh subsets is caused by a general increase in PD-1 expression in children with type 1 diabetes or AAb+ children.