CD4 and HIV-1 infection: To investigate whether GPR15 expression on these T cell subsets is altered in the context of HIV-1 infection, we analyzed surface expression of GPR15 on CCR7+CD45RA− central memory, CCR7−CD45RA− effector memory and CCR7+CD45RA+ naïve CD4+ T cells (Figures 1A and 1B) from healthy donors and HIV-1 infected individuals.