ab21402

Longitudinal analysis of serum KL-6 levels in patients with systemic sclerosis: association with the activity of pulmonary fibrosis

K. Yanaba^1,2, M. Hasegawa¹, Y. Hamaguchi¹, M. Fujimoto³, K. Takehara¹, S. Sato¹

¹Department of Dermatology, Kanazawa University Graduate School of Medical Science, Kanazawa; ²Department of Dermatology, The Jikei University School of Medicine, Tokyo; and ³Department of Regenerative Medicine, Research Institute, International Medical Center of Japan, Tokyo, Japan.

ABSTRACT
Objective
To determine whether changes in serum KL-6 levels reflect the activity of pulmonary fibrosis (PF) in patients with systemic sclerosis (SSc).

Methods
KL-6 levels were determined by ELISA in 39 SSc patients. In a retrospective longitudinal study, 250 serum samples were analyzed during a follow-up period of 0.3-6.1 years.

Results
KL-6 levels at the first visit were higher in patients with SSc, especially with PF, compared with healthy controls. In the longitudinal study, KL-6 levels in 4 patients with anti-topo I Abs increased rapidly, parallel to the progression of PF. Four patients with inactive PF exhibited elevated, but stable levels of KL-6 during the follow-up. The 31 patients with almost normal KL-6 levels during the follow-up exhibited no deterioration or new onset of PF.

Conclusion
Rapidly increased serum KL-6 levels during disease course were associated with new onset or deterioration of PF.

Key words
Systemic sclerosis, KL-6, pulmonary fibrosis, disease activity, longitudinal study.

Please address correspondence and reprint requests to: Shinichi Sato, MD, PhD, Department of Dermatology, Kanazawa University Graduate School of Medical Science, 13-1 Takaramachi, Kanazawa, Ishikawa 920-8641, Japan.
E-mail: s-sato@med.kanazawa-u.ac.jp