IL2 and HIV infectious disease: Based on the findings that (1) HIV-1 disease progression is characterized by loss of production of IL-2 and TNF-α concomitant with increased IL-4 and IL-10 production and (2) HIV-exposed seronegative individuals (HESI) exhibited a strong Th1 response, Clerici and Shearer proposed that the Th1 to Th2 switch in HIV infection contributes to the dysregulation of the immune system, such that resistance to HIV infection or HIV disease progression is determined using the Th1 dominance [109].