CD4 and infection: In association with decreased levels of IL-12, the IL-18 promotes the differentiation of Th2 CD4+ T-cells in the later stages of the infection; in addition, it has been reported that IL-18 induce destruction of the central nervous system and other tissues, thus it has been suggested that elevated levels of IL-18 are associated with and may contribute to a virological treatment failure and disease progression in PLWHIV [30, 64].