IL17A and leprosy: In recent times, the IL-17 cytokines are emerging as key player in immune responses.[53] IL-17 is uniquely secrete by Th17 cells, which are critical to the adaptive immune response against bacterial and fungal infections, and also contribute to the pathogenesis of several inflammatory diseases, by recruiting neutrophils, activating macrophages, and enhancing Th1 effector cells.[54] IL-17 has also been observed as associated cytokine with leprosy reactions.[55] TL patients with type 1 reactions (T1R) showed down-regulate of IL-17.