Surface expression of PSR protein on human lung microendothelial cells: analysis by flow cytometry. Following incubation of endothelial cells for 6 hours in the absence (left column) or presence of IL-1α (10 ng/mL, middle column) or TNF-α (10 ng/mL, right column), cells were harvested, labeled with desired test antibody or an equivalent amount of an isotype-matched negative control, and analyzed by flow cytometry as detailed. Endothelial cells labeled with mouse monoclonal antibody against PSR from Cascade Bioscience (Bi-iii), Dr Henson's laboratories (Ci-iii), and a rabbit polyclonal antibody against PSR from Sigma Chemical (Di-iii) are shown. Results presented are from a representative experiment repeated 4 to 6 times with similar results. Endothelial cells labeled with appropriate isotype-matched negative control antibodies are shown in panels Ai-iii. The red and blue lines are the negative histogram profiles for the rabbit polyclonal and mouse monoclonal antibodies, respectively. Markers M1 and M2 are the positive histogram regions for the anti-PSR monoclonal and polyclonal antibodies that were set up with endothelial cells labeled with appropriate isotype-matched negative control antibodies. Percentage marker-positive cells is shown in each panel. HT1080 cells analyzed concomitantly demonstrated 71% to 79% positivity with all 3 antibodies.