Aggregation in WAS platelets. Platelets from control and WAS patients were prepared as described in Materials and Methods. Care was taken to ensure that platelets were prepared in exactly the same way and used at the same concentration. The experiments in (A) through (C) were performed on the same day in the absence of indomethacin at a platelet concentration of 2 × 108/mL. Collagen is unable to stimulate aggregation in the presence of indomethacin; similar results were observed for thrombin in the presence of indomethacin. The experiments in (D) and (E) were performed on a separate donor in the presence of indomethacin and at a lower platelet concentration of 0.7 × 108/mL. The mean aggregation over the length of the concentration response curve to collagen was measured. The results are representative of between 2 and 5 separate experiments.
