title: Interleukin-18 as an efficient marker for remission and follow-up in patients with inactive adult-onset Still's disease.
abstract: OBJECTIVE
  Diagnosis of adult-onset Still's disease (AOSD) is difficult because of a lack of pathognomonic findings and markers. The aim of this study was to investigate the efficacy of interleukin (IL)-18 and free IL-18 in the diagnosis and follow-up of patients with AOSD.
  
  
  METHODS
  Levels of inflammatory cytokines, IL-18, IL-18 binding protein (IL-18BP), and free IL-18 were compared in 80 AOSD patients and 90 controls. The AOSD patients were divided into active and inactive groups according to disease activity, and the inactive patients were subdivided into a remission subgroup and a low disease activity subgroup. We compared erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), ferritin, IL-18, and free IL-18 as disease activity markers in the AOSD patients. Serial serum levels of activity markers were measured in 52 of the 80 AOSD patients at 3- to 6-month intervals.
  
  
  RESULTS
  There were significantly higher levels of IL-18 and free IL-18 in the AOSD patients than in the controls. IL-18 and free IL-18 were significantly higher in the active group than the inactive group (p < 0.001 for all). Unlike other activity markers, IL-18 and free IL-18 levels in the low disease activity subgroup were significantly higher than those in the remission subgroup within the inactive group (p = 0.004 and 0.005, respectively). During serial follow-up, ferritin and IL-18 showed a significant decrease in the responder and remission subgroup.
  
  
  CONCLUSIONS
  IL-18 might be an efficient marker for diagnosis and follow-up of AOSD and might also be a useful predictor of remission, especially in clinically inactive patients.
authors.affiliation: Division of Rheumatology, Centre for Rheumatism, Inha University Hospital , Incheon , Republic of Korea.
authors.forename: K-H
authors.initials: KH
authors.lastname: Jung
authors.forename: J-J
authors.initials: JJ
authors.lastname: Kim
authors.forename: J-S
authors.initials: JS
authors.lastname: Lee
authors.forename: W
authors.initials: W
authors.lastname: Park
authors.forename: T-H
authors.initials: TH
authors.lastname: Kim
authors.forename: J-B
authors.initials: JB
authors.lastname: Jun
authors.forename: D H
authors.initials: DH
authors.lastname: Yoo
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D016207:Cytokines / Q000097:blood; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007166:Immunosuppressive Agents / Q000627:therapeutic use*; D020382:Interleukin-18 / Q000097:blood*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012074:Remission Induction; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D016706:Still's Disease, Adult-Onset / Q000097:blood / Q000175:diagnosis* / Q000188:drug therapy*
chemical_list: D015415:Biomarkers; D016207:Cytokines; D007166:Immunosuppressive Agents; D020382:Interleukin-18