Serum S100A8/A9, but not follistatin-like protein 1 and interleukin 18, may be a useful biomarker of disease activity in adult-onset Still's disease.
OBJECTIVE
S100A8/A9, follistatin-like protein 1, and interleukin 18 (IL-18) have been suggested as biomarkers of disease activity in patients with systemic juvenile idiopathic arthritis or adult-onset Still's disease (AOSD). We investigated the clinical significance of these factors in AOSD.


METHODS
Blood samples were collected from 36 patients with AOSD, 40 patients with rheumatoid arthritis (RA), and 33 healthy controls. Of the patients with AOSD, followup samples were collected from 16 patients after resolution of disease activity.


RESULTS
Serum levels of S100A8/A9 (11.77 ± 8.84 μg/ml) in AOSD patients were higher than those in RA patients (3.53 ± 3.43 μg/ml; p < 0.001) and controls (2.49 ± 1.83 μg/ml; p < 0.001). Follistatin-like protein 1 levels in AOSD were not different from those in RA and controls. IL-18 levels in AOSD (7560.3 ± 7577.6 pg/ml) were higher than those in RA (217.7 ± 292.1 pg/ml; p < 0.001) and controls (139.2 ± 86.2 pg/ml; p < 0.001). The sensitivity and specificity of IL-18 for diagnosing AOSD was highest with a cutoff value of 366.1 pg/ml. Serum S100A8/A9 correlated with leukocyte count, erythrocyte sedimentation rate, C-reactive protein, ferritin, and systemic disease score; however, IL-18 correlated only with ferritin and systemic disease score. S100A8/A9 was decreased after disease activity was resolved in followup of AOSD patients (9.96 ± 7.35 μg/ml in active AOSD vs 3.6 ± 4.77 μg/ml in resolved cases; p = 0.001). The change of S100A8/A9 was well correlated with that of systemic disease score.


CONCLUSIONS
The data suggest that serum S100A8/A9 may be a useful biomarker for evaluating disease activity in patients with AOSD.
Department of Rheumatology and BK21 Division of Cell Transformation and Restoration, Ajou University School of Medicine, Suwon, South Korea 443-721.
Hyoun-Ah
HA
Kim
Jeong-Mi
JM
An
Jin-Young
JY
Nam
Ja-Young
JY
Jeon
Chang-Hee
CH
Suh
D000328:Adult; D017668:Age of Onset; D001172:Arthritis, Rheumatoid / Q000097:blood; D015415:Biomarkers / Q000097:blood; D001799:Blood Sedimentation; D002097:C-Reactive Protein / Q000032:analysis; D040501:Calgranulin A / Q000097:blood*; D040502:Calgranulin B / Q000097:blood*; D005260:Female; D005293:Ferritins / Q000097:blood; D038702:Follistatin-Related Proteins / Q000097:blood*; D006801:Humans; D020382:Interleukin-18 / Q000097:blood*; D007958:Leukocyte Count; D008297:Male; D008875:Middle Aged; D012720:Severity of Illness Index; D016706:Still's Disease, Adult-Onset / Q000097:blood* / Q000175:diagnosis
D015415:Biomarkers; D040501:Calgranulin A; D040502:Calgranulin B; D038702:Follistatin-Related Proteins; D020382:Interleukin-18; D002097:C-Reactive Protein; D005293:Ferritins