ENTPD1 and myalgic encephalomeyelitis/chronic fatigue syndrome: Interestingly, despite the reduced number of samples analyzed, a trend towards increased levels of CD39+CD73+ Treg cells in ME/CFS cases compared with healthy controls was observed (p = 0.06, Figure 4C), a finding that identifies this new subset of Treg cells, which are also relevant in other chronic pathologies (25) as possible candidate markers that should be explored further in biobanked specimens.