PF3 activity in normal subjects and beta-thalassemia trait

Platelet factor 3 (PF3) is a platelet membrane component that plays an important role in the activation of the coagulation mechanism. Whenever platelet activation occurred, PF3 is released and participates in thrombin formation. Erythrocyte membrane fraction has also some PF3 like activity, and in abnormal erythrocyte membrane disorders, eg thalassemia, some of the membrane fraction accelerates platelet activation by increasing the PF3 activity. Formerly it was difficult to measure the PF3 activity in plasma. Recently a sensitive chromogenic test to determine the PF3 activity, which could detect the changes in PF3 activity with time, was introduced. This study was done to observe the effect of abnormal erythrocyte on platelet activation. The results obtained using the chromogenic method are the following: whole blood taken from normal subjects showed OD 0.11 +/- 0.06 at 0 minutes after blood collection and then increased significantly (p < 0.01) to 0.21 +/- 0.10 after 90 minutes, while the platelet count did not differ significantly (p > 0.05). Those results showed that there were some platelet activation after 90 minutes as seen by the increased PF3 activity, with no significant change in platelet counts. In beta-thalassemic trait subjects the PF3 activity in whole blood at 0 minutes did not differ significantly compared to the normal subjects, but after 90 minutes it was significantly higher (p < 0.01), OD 0.52 +/- 0.35. However the PF3 in platelet rich plasma at 90 minutes did not increase. The platelet count after 90 minutes was significantly decreased (p < 0.01) This result suggest that the increase in PF3 activity was caused by the role of the abnormal erythrocytes.