Longitudinal analysis of immune abnormalities in varying severities of Chronic Fatigue Syndrome/Myalgic Encephalomyelitis patients

Abstract

Background: Research has identified immunological abnormalities in Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME), a heterogeneous illness with an unknown cause and absence of diagnostic test. There have been no CFS/ME studies examining innate and adaptive immune cells longitudinally in patients with varying severities. This is the first study to investigate immune cells over 6months while also examining CFS/ME patients of varying symptom severity. Methods: Participants were grouped into 18 healthy controls, 12 moderate and 12 severe CFS/ME patients and flow cytometry was used to examine cell parameters at 0 and 6months. Results: Over time, iNKT CD62L expression significantly increased in moderate CFS/ME patients and CD56 bright NK receptors differed in severe CFS/ME. Naïve CD8 + T cells, CD8 - CD4 - and CD56 - CD16 - iNKT phenotypes, γδ2T cells and effector memory subsets were significantly increased in severe CFS/ME patients at 6months. Severe CFS/ME patients were significantly reduced in CD56 bright CD16 dim NKG2D, CD56 dim CD16 - KIR2DL2/DL3, CD94 - CD11a - γδ1T cells and CD62L + CD11a - γδ1T cells at 6months. Conclusions: Severe CFS/ME patients differed from controls and moderate CFS/ME patients over time and expressed significant alterations in iNKT cell phenotypes, CD8 + T cell markers, NK cell receptors and γδT cells at 6months. This highlights the importance of further assessing these potential immune biomarkers longitudinally in both moderate and severe CFS/ME patients.