CD4 and myalgic encephalomeyelitis/chronic fatigue syndrome: In our cohort, CD4 T cells from CFS individuals and controls showed similar levels of naïve (CD45RA+CCR7+CD27+CD28+), central (CD45RA–CCR7+CD27+CD28+), transitional (CD45RA–CCR7-CD27+CD28+), effector (CD45RA–CCR7-CD27+CD28-) and terminally differentiated memory (CD45RA-CCR7-CD27-CD28-) cells (Figure 3A and B).