The presence of inflammatory mediators in periodontitis, such as IL-1, IL-1 β, IL-4, IL-6, IL-8, IL-10, TNF and IFN-γ, together with macrophages sensitized by M. leprae in the bloodstream can exacerbate the host’s immune response, triggering the leprosy reaction (Motta et al. 2011; Cortela et al. 2015). The gene discussed is IL4; the disease is leprosy.