Leukotrienes (LTs) exert an inhibitory effect on the early stages of HIV-1 infection in monocyte-derived microglial-like cells (MDMis). Cells were either left untreated, or treated with increasing concentrations of LTB4 (left panels) or LTC4 (right panels), either 45 minutes before virus exposure or 2 h to 48 h post infection, as indicated. Cells were first washed extensively with phosphate-buffered saline (PBS) and then infected at 45 minutes after addition of LTs. MDMis were washed a second time at 2 h after infection before adding LTs. No washes were carried out before adding LTs at 24 h and 48 h. Infection was carried out with a luciferase encoding reporter virus pseudotyped with JR-FL (A) or vesicular stomatitis virus envelope glycoprotein G (VSV-G) envelope (B). The less active analogs (called LAA) 20-carboxy-LTB4 and N-acetyl LTE4 were used as negative controls for LTB4 and LTC4, respectively. The extent of virus infection was estimated by measuring virus-encoded luciferase activity at 7 days post infection. The results shown represent the means ± SD calculated from three, or four (bottom right panel), independent experiments with triplicate samples and are expressed as the percentage of luciferase activity with respect to non-treated cells (*P < 0.05).