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 6 months 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 6 months.

Results: Over time, iNKT CD62L expression significantly increased in moderate CFS/ME patients and CD56bright 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 6 months. Severe CFS/ME patients were significantly reduced in CD56brightCD16dim NKG2D, CD56dimCD16− KIR2DL2/DL3, CD94−CD11a− γδ1T cells and CD62L+CD11a− γδ1T cells at 6 months.

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 6 months. This highlights the importance of further assessing these potential immune biomarkers longitudinally in both moderate and severe CFS/ME patients.