Figure 4

Trans -dominant cellular inhibition of DC-SIGN transmission of HIV-1 (A) Transmission of HIV-1 by Raji/DC-SIGN cells was inhibited in the presence of K562 cells. Donor cells alone (1.25 × 10⁵) or two mixed types of donor cells (1.25 × 10⁵ for each, 1:1 ratio) as indicated were incubated with HIV-Luc/ADA. The HIV-1 capture and transmission assay using transwell plates was performed as described for Figure 1. Hut/CCR5 cells were used as targets and DC-SIGN-negative parental cells were used as controls. +, K562 cells present; -, absent. Each data set represents the mean of three separate wells of infected cells. One representative experiment out of three is shown. cps, counts per second. (B) Direct infection of Hut/CCR5 targets cells with HIV-Luc/ADA in the presence of the Raji or K562 cells. Hut/CCR5 cells alone (1 × 10⁵) or mixed with Raji or K562 cells (1 × 10⁵ for each, 1:1 ratio) were incubated with HIV-Luc/ADA (2.5 × 10⁴ IU) for 2 h at 37°C, washed with PBS, then cultured 2 days before lysis. One representative experiment out of two is shown. (C) Trans inhibition of HIV-1 transmission mediated by Raji/DC-SIGN cells requires contact with K562 cells. The HIV-1 capture and transmission assay using the transwell plates was performed as described for Figure 1. The different types of donor cells were either mixed or separated by the permeable membrane as illustrated. DC-SIGN-negative parental cells were used as controls. Hut/CCR5 cells were used as target cells, which were co-cultured with donor cells below the membrane inserts. K562 cells were placed on top of the membrane inserts in the separated donor cell group. +, K562 cells present; -, absent. Each data set represents the mean of three separate wells of infected cells. One representative experiment out of three is shown.