Saleem A, Fretz K
Am J Clin Pathol. 1977 Jun;67(6):533-6. doi: 10.1093/ajcp/67.6.533.
Platelet factor 4 (heparin neutralizing) activity shortens the thrombin time of a heparinized plasma. In the proposed procedure (I) a heparin thrombin time curve is constructed by adding gradually increasing amounts of heparin to a commercial plasma substrate and determining thrombin times, (2) a suitable concentration of heparin that gives highest reproducible thrombin time is selected and added to the substrate, (3) thrombin times are determined for the heparinized substrate before and after addition of a test material containing platelet factor 4. The two thrombin times are converted to heparin concentration by reference to the heparin thrombin time curve. The difference in heparin concentrations represents platelet factor 4 activity. When lyophilized commercial plasma is used as substrate larger quantities of heparin can be employed in the system, resulting in improved sensitivity and precision.
血小板第4因子（肝素中和）活性可缩短肝素化血浆的凝血酶时间。在所建议的方法中：（1）通过向市售血浆底物中逐渐增加肝素量并测定凝血酶时间来构建肝素凝血酶时间曲线；（2）选择能给出最高可重复凝血酶时间的合适肝素浓度并添加到底物中；（3）在添加含血小板第4因子的测试材料之前和之后，测定肝素化底物的凝血酶时间。通过参考肝素凝血酶时间曲线，将这两个凝血酶时间转换为肝素浓度。肝素浓度的差异代表血小板第4因子活性。当使用冻干的市售血浆作为底物时，系统中可使用大量肝素，从而提高灵敏度和精密度。
