Following in vitro polyclonal stimulation by anti-CD3/CD28, IL1-β, and IL-23, the subsets of CCR6+ CD4 T cells show higher expression of CD4 and CXCR4 than CCR6- cells, which may contribute to the greater permissiveness of Th17 cells to HIV infection (44). Here, CXCR4 is linked to HIV infectious disease.