CD41^–CD61^–, PI^– events in the anti-CD41 mAb–treated mice label with vital dye fluorescein diacetate. Blood cells were analyzed by flow cytometry for their expression of CD41 and CD61 (platelet) and then were fluorescence-labeled with the vital dye fluorescein diacetate. (A) Blood cell labeling prior to addition of fluorescein diacetate. (B) Blood cell labeling after 10 minutes of incubation with fluorescein diacetate. The CD41^–CD61^–, PI^– cells are magenta and those cells labeling with fluorescein diacetate are green. The gray events comprise all cells that are not CD41^–CD61^–,PI^– cells. The inset % is the percentage of CD41^–CD61^–,PI^– cells that are labeled with fluorescein diacetate.