(A) Binding of HIV-1 to monocytes with or without SLPI. Monocytes were either pretreated with SLPI (▧) or DMEM (▪) for 30 minutes at 37°C and then virus was added, or alternatively, virus + SLPI was added to cells concurrently (□) for 30 minutes at 37°C. Cells were washed twice with PBS and resuspended in 0.5% Triton X-100, and cell-bound virus was assayed by p24 ELISA. The negative control (neg) was cells with no virus or SLPI added. Values are the mean ± SD; n = 4. (B) Virus titer produced from cells treated with SLPI. Monocytes infected with HIV-1Ba-L 1 hour in the absence or presence of SLPI 5 μg/mL were cultured for 18 days. Virus from the culture medium on day 18 was collected and titrated in fresh monocytes. For titration, virus was initially equalized based on RT values. Viral titers are from SLPI-treated cells (▧) or untreated cells (▪). Final dilution of virus is indicated under each bar. p24 values are the mean ± SD (n = 3) from day 21 postinfection.
