-Original-

Serum Interleukin-18 Provides a Clue to the Diagnosis of Adult-Onset Still's Disease: Findings from 6 Japanese Patients with Adult-Onset Still's Disease

Azusa Ogita¹, Shin-ichi Ansai¹ and Hidehisa Saeki²

¹Division of Dermatology, Nippon Medical School Musashi Kosugi Hospital, Kanagawa, Japan
²Department of Dermatology, Nippon Medical School Hospital, Tokyo, Japan

Background: Adult-onset Still's disease (AOSD) is a systemic autoinflammatory disorder accompanied by skin eruption. However, typical skin eruptions, such as evanescent, salmon-pink erythema, are not specific to AOSD and dermatologists often face difficulty in diagnosing AOSD. In this study, we examined serum IL-18 levels as well as IL-6, ferritin and C-reactive protein in 6 Japanese patients with AOSD.
Methods: Serum levels of IL-6 and IL-18 were evaluated in the acute phase and at the time of remission. Serum levels of IL-6 were analyzed using a commercial chemiluminescent enzyme immunoassay (CLEIA; SRL, Tokyo, Japan). Serum IL-18 levels were measured using a commercial ELISA kit (Medical & Biological Laboratories Co., LTD. Nagoya, Japan).
Result: In active AOSD, serum ferritin levels and CRP levels were above normal range in 6 patients. In remission, serum ferritin levels of 3 patients were slightly above the normal range, while CRP serum levels of 6 patients were all normalized. Serum IL-18 levels were markedly elevated in 5 cases during the acute phase. In remission, serum IL-18 levels remained at higher values than the normal range in 5 cases. Serum IL-6 levels were also highly elevated in 5 patients in active AOSD and became normalized in remission except in case 2.
Conclusion: High levels of serum IL-18 will be a clue to the diagnosis of AOSD. CRP is also useful biomarker for monitoring disease activity compared with IL-6 and IL-18.

J Nippon Med Sch 2022; 89: 114-118

Keywords
steroid resistant, Interleukin-18, Interleukin-6, Adult-onset Still's disease

Correspondence to
Azusa Ogita, MD, Division of Dermatology, Nippon Medical School Musashi Kosugi Hospital, 1-396 Kosugi-cho, Nakahara-ku, Kawasaki, Kanagawa 211-8533, Japan
azu@nms.ac.jp

Received, February 8, 2021
Accepted, April 30, 2021