KLRG1 and myalgic encephalomeyelitis/chronic fatigue syndrome: Conversely, in moderately severe ME/CFS patients from a separate study, the ME/CFS T cells showed an increased KIR2DL5 expression (part of the KIR family) on CD4+ cells, but decreased CD8+KLRG1+ and CD4+KLRG1+ population frequencies [176].