FIG. 3.

Inhibition by RgpA of HLA-DR expression induced in HUVE cells is thiol mediated. RgpA was preincubated with or without the thiol-protease inhibitor TLCK for 1 h at 37°C and then dialyzed exhaustively against PBS. rIFN-γ (3 nM) and the TLCK-treated RgpA (60 nM) were simultaneously added to HUVE cells seeded at a density of 10⁵ cells/cm² and then incubated for 4 days in supplemented medium containing 20% FCS as described in Materials and Methods. After 4 days of culture, cells were removed and analyzed for HLA-DR expression by flow cytometric analysis. The cell number (y axis) versus the logarithm of fluorescence (x axis) is represented. The data are representative of three separate experiments.