Complement activation in a model of chronic fatigue syndrome.
BACKGROUND
A need exists to identify biological markers in chronic fatigue syndrome (CFS).


OBJECTIVE
To use an exercise and/or allergen challenge to induce the symptoms of CFS and to identify a biological marker that correlates with these symptoms.


METHODS
Patients with CFS (n = 32) and age-matched, normal control patients (n = 29) exercised for 20 minutes on a stationary bike at 70% of their predicted max work load (Watts). Patients from each group with positive skin test results were also challenged with intranasally administered relevant allergens. Symptoms were recorded for 2 weeks before and 1 week after each challenge, using 3 different instruments. Blood samples were taken before, and 0, 1, 6, and 24 hours after challenges. Levels of complement split products, cell-associated cytokines, and eosinophilic cationic protein were measured. Mean preexercise and postexercise symptom scores were evaluated for each group.


RESULTS
Exercise challenge induced significant increases of the complement split product C4a, but not C3a or C5a, at 6 hours after exercise only in the CFS group (P <.01), regardless of allergy status. Mean symptom scores were significantly increased after exercise through the use of a daily diary (P <.03) and a weekly diary (P <.01) for the CFS group only. Mean scores for the Multidimensional Fatigue Inventory categories "reduced activity" and "mental fatigue" were significantly increased in the CFS group only (P <.04 and P <.02, respectively).


CONCLUSIONS
Exercise challenge may be a valuable tool in the development of diagnostic criteria and tests for CFS. Establishment of a role for complement activation products as markers or participants in production of illness require further study.
Sorensen
Bristol
B
Department of Pediatrics, National Jewish Medical and Research Center, Denver, CO, USA.
Streib
Joanne E
JE
Strand
Matthew
M
Make
Barry
B
Giclas
Patricia C
PC
Fleshner
Monika
M
Jones
James F
JF
D000328:Adult; D000485:Allergens / Q000276:immunology; D016022:Case-Control Studies; D003167:Complement Activation; D015934:Complement C4a / Q000032:analysis; D015444:Exercise; D015673:Fatigue Syndrome, Chronic / Q000097:blood* / Q000175:diagnosis / Q000276:immunology / Q000503:physiopathology; D005260:Female; D006632:Histamine; D006801:Humans; D008297:Male; D009994:Osmolar Concentration; D013997:Time Factors
D000485:Allergens; D015934:Complement C4a; D006632:Histamine