CD8A and myalgic encephalomeyelitis/chronic fatigue syndrome: Comparative analysis was also performed using publicly available scRNA-seq datasets from idiopathic ME/CFS patients.<h4>Results</h4>Based on transcriptional signatures, LC-ME/CFS patients exhibited a marked reduction in naïve CD4<sup>+</sup> and CD8<sup>+</sup> T cells, regulatory T cells, MAIT cells, and γδ T cells, accompanied by an expansion of effector T cells.