Fig 4.

OM-5 downregulates surface ACE2 protein expression in epithelial cells. Vero E6 (A-C) and Calu-3 (D-F) cells were treated with OM-85 (0.48 or 1.92 mg/mL) for 72 hours and assessed for ACE2 protein expression by flow cytometry with ACE2-specific mAbs and relevant isotype controls. A and D, Representative ACE2 flow cytometry plots (shaded area: isotype control; thin line: PBS-treated cells; thick line: cells treated with OM-85, 1.92 mg/mL); B and E, ACE2 MFI and percentages of ACE2⁺ cells in PBS- and OM-85–treated cells (Fig 4, C and F). Data are from 1 experiment with 4 samples/condition. An unpaired, 2-tailed t test was used for statistical analysis after testing for normality of sample distribution. MFI, Mean fluorescence intensity.