CD4 and myalgic encephalomeyelitis/chronic fatigue syndrome: The present study has shown a significant increase in CD8− CD4− iNKT cells in severe CFS/ME patients, suggesting a possible regulatory mechanism where cytotoxic activities may be enhanced in iNKT cells as a regulatory response to the reduced cytotoxic activity that has been consistently documented in NK cells and CD8+ T cells of CFS/ME patients [3, 4, 6, 8, 10].