CD4 and dengue disease: Additionally, Sánchez-Vargas et al. showed that patients with severe dengue also excessively produce IL-17A [107], a pro-inflammatory cytokine produced by Th17 cells, a subset of CD4+ T helper cells; an exaggerated expression of IL-17A correlates with dengue complications caused by activating neutrophils and inducing the release of inflammatory mediators from these cells.