Schematic diagram of the HIV-1–transfer assay. Immature MoDCs were pulsed with primary R5 HIV-1 isolates for 2 hours, thoroughly washed, and added to uninfected primary autologous PHA-activated CD4 T lymphocytes. The percentage of HIV-1–infected cells in each cell population was determined on the basis of intracellular viral p24 Ag detection by flow cytometry.