CD4 and HIV-1 infection: To assess HIV-1 infection of the mucosal immune cells known to be involved in initial infection (2), i.e. DCs (45) and T cells (37), the emigrating cells were collected after 3-5 days of infection followed by flow cytometric investigation to determine the amount of HIV infected (p24 gag+) DCs (CD1a+ or CD1c+), and T cells (CD3+CD4+).