CD4 and myalgic encephalomeyelitis/chronic fatigue syndrome: In a more detailed phenotypic analysis of CD4+ and CD8+ T cell compartments by analysis of CD28 and CD57 alongside CCR7 and CD45RA, we found that there were no differences in the CD4+ T cell differentiation subpopulations in people with ME/CFS, although there were altered cell population frequencies in people with MS (Figure 5A).