RAPID REMOVAL OF PLATELETS FROM PLASMA UTILIZING THE HEPCHECK(TM) HEPARIN REMOVAL FILTER

We investigated whether Hepchek(TM) heparin removal filters could remo ve residual platelets from platelet-poor plasma (PPP) without compromi sing samples for lupus anticoagulant (LA) testing. Furthermore we asse ssed what effect, if any, plasma filtration has on various clotting te sts that form the foundation for LA testing. Citrated blood was obtain ed from 35 normal donors. Two sets of citrated tubes were processed in order to obtain PPP. Citrated blood was also obtained from a single d onor to check the actual amounts of platelets removed by the Hepcheck( TM) filtration device. One set of PPP samples was filtered using the H epchek(TM) filter device and the other was not processed, i.e. unfilte red. Prothrombin time (PT), activated partial thromboplastin time (APT T), and kaolin clotting time (KCT) were performed on both unfiltered a nd filtered samples that were tested immediately and after freezing at -70 degrees C for 24 h. Platelet counts on the single donor's citrate d plasma were dramatically reduced after filtration. PT and APTT value s showed small but statistically significant differences between unfil tered and filtered plasmas whether these were fresh or frozen samples. However, these differences mere not clinically significant. KCT darn showed statistical and clinical differences between unfiltered and fil tered plasmas whether fresh or frozen plasmas were used. In contrast, KCT values were similar if unfiltered, fresh plasmas or filtered, froz en plasmas were used. Coagulation factor assays for factors VIII, IX a nd X were performed on both sets of PPP samples after freezing to dete rmine if the filtration device affected these levels and would as a re sult, compromise APTT based lupus testing. Factor IX levels demonstrat ed a loss of activity following use of the device but no change was ob served in factor VIII or factor X. Von Willebrand factor antigen and f unction as well as multimer structure were not affected by the filtrat ion device in 10 normal donors. Filtering plasmas of two donors with a history of an LA dramatically prolonged clotting times for APTT, Dilu te Viper Venom Time, mixing studies, and STACLOT(R) LA tests in compar ison with unfiltered plasmas. The data indicate that plasma filtration using the Hepchek(TM) device does not adversely affect coagulation te sting. Furthermore samples requiring testing for the lupus anticoagula nt can be filtered and subsequently frozen and compare favorably with freshly processed samples.