2. Case Presentation
We previously reported two cases with chikungunya fever after traveling to Cook Island.3 The elevated serum IL-6, IL-17, IL-21, and IL-23 levels have been reported in patient with chronic arthritis after chikungunya fever [1,2]. Recent findings in psoriatic arthritis revealed the elevated serum IL-36 during arthritis [4]. IL-36 is a relatively newly found cytokine belonging to the IL-1 family, whose involvement in various diseases is still poorly understood. In the current study, to evaluate the involvement of IL-36 in patients with chikungunya fever, stocked serum from the previously reported two cases [1] at the initial visit, 7 days, and 56 days later were used to measure IL-36α and IL-36βconcentration. Two cases were siblings, and the brother developed pain in his neck and ankle joints on the second day back to Japan, but fever was not detected. Sister developed fever soon after returning to Japan, with severe arthralgia and leg edema. The arthralgia persisted for about a year. IL-36α and IL-36β were measured in the patient’s serum using human IL-36α/IL-1F6 and IL-36β/IL-1F8 DuoSet ELISA® (R&D Systems, Minneapolis, MN, USA). At the initial visit, IL-36α was higher in the sister, who had more fever and arthralgia symptoms than her brother. 7 days later, both had higher levels than at the initial visit, but the brother, whose symptoms of Chikungunya fever appeared later, had a larger increase than at the initial visit. After 56 days, both decreased to about half of the peak value. IL-36β was highest at the first visit for both patients and gradually decreased (Figure 1).