CD4 and infection: Moreover, inflammatory cytokines such as IL-2, TNF (tumor necrosis factor), IL-6, and IL-18, and chemokines CC-chemokine ligand 19 (CCL19) and CCL21 are elevated during treated HIV disease; this provides the inflammatory environment that render CD4+ T cells more susceptible to infection in tissues of infected subjects 54, 57–59 (Fig.1).