Serum levels of interferon‐γ, tumour necrosis factor‐α, soluble interleukin‐6R and soluble cell activation markers for monitoring response to treatment of leprosy reactions

Summary Identifying pathogen and host‐related laboratory parameters are essential for the early diagnosis of leprosy reactions. The present study aimed to clarify the validity of measuring the profiles of serum cytokines [interleukin (IL)‐4, IL‐6, IL‐10, interferon (IFN)‐γ and tumour necrosis factor (TNF)‐α], the soluble IL‐6 receptor (sIL‐6R), soluble T cell (sCD27) and macrophage (neopterin) activation markers and Mycobacterium leprae ‐specific anti‐PGL‐I IgM antibodies in relation to the leprosy spectrum and reactions. Serum samples from 131 Indonesian leprosy patients (82 non‐reactional leprosy patients and 49 reactional) and 112 healthy controls (HC) from the same endemic region were investigated. Forty‐four (89·8%) of the reactional patients had erythema nodosum leprosum (ENL) while only five (10·2%) had reversal reaction (RR). Follow‐up serum samples after corticosteroid treatment were also obtained from 17 of the patients with ENL and one with RR. A wide variability in cytokine levels was observed in the patient groups. However, IFN‐γ and sIL‐6R were elevated significantly in ENL compared to non‐ENL patients. Levels of IFN‐γ, TNF‐α and sIL‐6R declined significantly upon corticosteroid treatment of ENL. Thus, although the present study suggests limited applicability of serial measurement of IFN‐γ, TNF‐α and sIL‐6R in monitoring treatment efficacy of ENL, reactions it recommends a search for a wider panel of more disease‐specific markers in future studies.