Immune and hemorheological changes in chronic fatigue syndrome

Abstract

Background: Chronic Fatigue Syndrome (CFS) is a multifactorial disorder that affects various physiological systems including immune and neurological systems. The immune system has been substantially examined in CFS with equivocal results, however, little is known about the role of neutrophils and natural killer (NK) phenotypes in the pathomechanism of this disorder. Additionally the role of erythrocyte rheological characteristics in CFS has not been fully expounded. The objective of this present study was to determine deficiencies in lymphocyte function and erythrocyte rheology in CFS patients.

Methods: Flow cytometric measurements were performed for neutrophil function, lymphocyte numbers, NK phenotypes (CD56(dim)CD16(+) and CD56(bright)CD16(-)) and NK cytotoxic activity. Erythrocyte aggregation, deformability and fibrinogen levels were also assessed.

Results: CFS patients (n = 10) had significant decreases in neutrophil respiratory burst, NK cytotoxic activity and CD56(bright)CD16(-) NK phenotypes in comparison to healthy controls (n = 10). However, hemorheological characteristic, aggregation, deformability, fibrinogen, lymphocyte numbers and CD56(dim)CD16(+) NK cells were similar between the two groups.

Conclusion: These results indicate immune dysfunction as potential contributors to the mechanism of CFS, as indicated by decreases in neutrophil respiratory burst, NK cell activity and NK phenotypes. Thus, immune cell function and phenotypes may be important diagnostic markers for CFS. The absence of rheological changes may indicate no abnormalities in erythrocytes of CFS patients.

Figure 1

Distribution of total leukocyte percentage in peripheral blood. The percentage distribution of lymphocytes subsets in peripheral blood samples of CFS patients (Black bars; n = 10) and healthy controls (White bars; n = 10) was measured using the flow cytometer. Total lymphocytes, monocytes and granulocytes were performed using coulter analysis of full blood counts. All samples were analysed within six hours of collection. Leukocyte gate was used in determining the distribution of the various lymphocyte subsets. All values are presented as % means ± SEM.

Figure 2

Determination of NK cell phenotypes in whole blood samples. NK cell phenotypes, CD56^dimCD16⁺ and CD56^brightCD16^-NK cells were determined by flow cytometry after separation from whole blood from CFS patients (white bars; n = 10) and control subjects (black bars; n = 10). The plots shown are gated on NK lymphocyte population. Data are the mean ± SEM. the symbol (*) denotes statistical significance.

Figure 3

Examination of neutrophils function in the presence of E. coli. The action of neutrophils phagocytic activity and respiratory burst function were compared between the two subject groups; CFS patients (black; n = 8) and controls (white; n = 8). RBF is respiratory burst while PF is phagocytic activity. Results represent the mean ± SEM the symbol (*) denotes statistical significance.

Figure 4

Assessment of erythrocyte aggregation in autologous plasma (A) and dextran solution (B). Peripheral blood samples from CFS patients (black; n = 10) and healthy controls (white; n = 10) assessed on measures of aggregation at stasis (M₀) and at low shear rate (M₁). Samples were measured after adjustment of hematocrit to 40% (A) following which they were washed and suspended in 3% dextran solution with a hematocrit 40% hematocrit adjustmnent (B). Samples were analysed within 12 hours of blood collection. Results are represented as mean ± SEM.

Figure 5

Assessment of erythrocyte deformability in CFS. Peripheral blood samples from CFS patients (black; n = 6) and healthy controls (white; n = 6) were assessed. Deformability was assessed at shear stresses from 0.5-20 Pa. The mean ± SEM are represented on the graph

Figure 6

Erythrocyte deformability after determination of EI_max and SS_1/2. EI_max (A) and SS_1/2 (B) of CFS patients (black; n = 6) and healthy controls (white; n = 6) were not significantly different. The values are the mean ± SEM of the two groups.