FIG. 2.

The syndecan-Fc hybrid molecule blocks HIV-1 infection of primary in vivo cell targets. (A) Blood-derived CD4⁺ T lymphocytes, macrophages, or DC (0.5 × 10⁶ cells) were exposed to JR-CSF (1 ng of p24) and syndecan-1-Fc or control Fc (5 μg/ml) for 1 day at 37°C and washed. The amount of virus released was monitored by measuring amounts of capsid protein in cell supernatants by p24 ELISA. The points are median values, and error bars represent standard errors of triplicates. The P values were calculated using a one-sided t test assuming equal variances. d, day. (B) Cells were serially diluted from 55,000 cells to 25 cells in 100 μl of complete medium. Fifteen microliters of the CellQuanti-MTTTM reagent was added, and cells were incubated for 4 h at 37°C. Then, 100 μl of the solubilization solution was added, and the plate was shaken for 1 h at room temperature. The A₅₇₀ was measured on a SpectraMax 384 Plus reader. To determine the cytotoxicity of Fc proteins, cells (55,000) were treated twice daily with 200 μg/ml of syndecan-1-Fc, Fc, or 0.01% saponin for a week. No washes were performed to maintain a continuous exposure of cells to Fc proteins. OD, optical density.