FIG. 7.

Flow cytometry analysis of intact and OM-permeabilized cells with anti-OmpA MAb SH16.2. Histograms of the occurrence of cells with various levels of fluorescence intensity are shown. Intact or OM-permeabilized cells were incubated with a 1/100 dilution of SH16.2, stained with fluorescein isothiocyanate-conjugated goat anti-mouse IgG, and analyzed for intensity of green fluorescence (MAb binding). OM permeabilization of cells was carried out by incubation of cells in 10 mM CaCl₂-10 mM MgCl₂ and 16% sucrose for 30 min on ice. Permeabilized cells were washed with a buffer containing 0.9% NaCl and 0.001 M EGTA. The total population analyzed was 10,000 bacteria for each strain. Abbreviations: PP, percent of cells staining positive; MFI, mean fluorescence intensity.