Monocytes of Chronic Fatigue Syndrome Patients, their Family Members without CFS, and Unrelated Healthy Donors: Searching for Differences

Abstract

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is characterized by fatigue that does not improve with rest and worsens with exertion. ME/CFS may involve inflammation in the brain and/or be associated with viral infections. Increased numbers of pro-inflammatory monocytes in blood are a hallmark of infection. Biomarkers for, and information about, the CFS disease process are greatly needed. Here we queried circulating monocytes. In a pilot study, CFS patients and family members without CFS from three families were compared in order to reduce genetic and environmental variables. The patients conformed to the Fukuda 1994 standards. Unrelated healthy control subjects matched to the patients were included in the study. Blood monocytes were stained and analyzed by flow cytometry: counted with TruCountR beads, or stained after isolation and overnight culture of isolated peripheral blood monocytes. M1 pro-inflammatory monocytes are CD16A negative, while anti-inflammatory monocytes are CD16A positive; CD2 is a marker for dendritic monocytes, and changes in forward scatter could indicate in vitro activation. Notably, there were statistically significant differences between the lower percentages of M1 monocytes of the CFS patients compared to the controls; however, these differences were not significant between the patients and their family members without CFS. Also, the CD16A MFIs of the patients' monocytes were lower compared to controls but not to family members. One conclusion is that it is important to include family members without CFS as a control group in the search for biomarkers to diagnose CFS.