Effect of CO donor on cell adhesion between U937 cells and VCAM-1-transfected B78H1 cells. A. Dot plot of flow cytometric analysis of cell aggregation. Cells were labeled with red and green fluorescent dyes. Next, cells were mixed at 0 time point. During data acquisition samples were maintained at 37°C, and continuously stirred with a magnetic stir bar. An increase in the number of aggregates was detected as green and red co-fluorescent particles indicated by the circular gate. B. Real-time cell aggregation plotted as % aggregates (Agg, %) versus time. The data were normalized to the non-specific aggregation determined as cell aggregation in the presence of excess unlabeled competitor (1 μM LDV). A representative experiment out of two experiments is shown. C. Statistical significance of the CO donor effect on cell aggregation. The aggregate percentage data from the last 5 min of the experiments (B) are compared using the unpaired t test. Means are significantly different (P < 0.05).