Treg cells defined as CD4+CD25++FOXP3+ or CD4+CD25++FOXP3+CD127– showed significantly higher percentages in CFS individuals (Figure 4B and data not shown), concomitant with lower levels of Ki67+ cells in CD4 T cells (Figure 4B). This evidence concerns the gene MKI67 and myalgic encephalomeyelitis/chronic fatigue syndrome.