Serum macrophage migration inhibitory factor levels in leprosy patients with erythema nodosum leprosum

Background: Erythema nodosum leprosum is an immune-mediated complication of leprosy which causes significant morbidity. Biomarkers in the pathogenesis of erythema nodosum leprosum are not yet fully determined. Aim: To determine macrophage migration inhibitory factor levels in the sera of leprosy patients with erythema nodosum leprosum and to correlate the same with clinical parameters. Methods: This cross-sectional study included 37 consecutive leprosy patients with active erythema nodosum leprosum and 31 age- and sex-matched controls. Detailed clinical history and examination findings were recorded including the severity and frequency of erythema nodosum leprosum. Slit skin smears and histopathologic examination were done in all patients at baseline. Serum macrophage migration inhibitory factor levels were determined using an enzyme-linked immunosorbent assay. Results: Most of our patients were males (78.4%) and suffering from lepromatous leprosy (27, 73%) with a mean initial bacillary index of 3.38 ± 1.36. Recurrent and chronic patterns of erythema nodosum leprosum were seen in 15 (40.5%) and 6 (16.3%) patients, respectively. Most (86.5%) of our patients presented with moderate to severe erythema nodosum leprosum. The mean serum macrophage migration inhibitory factor level was 21.86 ± 18.7 ng/ml among patients while it was 11.78 ± 8.4 ng/ml in the control group (P < 0.01). There were no statistically significant correlations of macrophage migration inhibitory factor levels with erythema nodosum leprosum frequency or severity. Limitation: Serum macrophage migration inhibitory factor levels in leprosy patients with no erythema nodosum leprosum and in patients with other inflammatory and autoimmune conditions were not assessed. Hence, this study falls short of providing the predictive value and specificity of higher macrophage migration inhibitory factor concentrations in serum as a biomarker of erythema nodosum leprosum. Conclusion: Macrophage migration inhibitory factor levels are elevated in erythema nodosum leprosum patients as compared to controls. A larger sample size and macrophage migration inhibitory factor gene polymorphism analysis will be needed to elucidate the role of this pro-inflammatory cytokine in erythema nodosum leprosum.