TROMBOSİTOPENİK HASTALARDA PLATELET YÜZEY ANTİJENLERİNİN AKIM SİTOMETRİ İLE İNCELENMESİ VE KANAMA DİYATEZİ İLE İLİŞKİSİNİN ARAŞTIRILMASI

Abstract

Bleeding is mainly associated with low platelet counts and platelet dysfunctions. Although there are several methods to evaluate platelet function, they require large amount of blood and platelet counts more than 150.000/µl. Flow cytometric analysis requires small amounts of blood sample and allows analyses of platelets in thrombocytopenic patients. Our aim was to examine platelet receptor responses to certain agonists in thrombocytopenic patients as an indicator of bleeding tendency using flow cytometry. Patients with diagnoses of AML, MDS and MM with platelet counts less than 100.000/µl were included in the study (n=40). Control samples were taken from healthy subjects (n=20). Complete blood count was performed with Unicell DXH 800 (Beckman Coulter), Accuri C6 (BD) was used for flow cytometric analyses. CD41a and CD42b were used to identify platelets. After stimulation with ADP and TRAP; CD63, CD62P, PAC-1 activation receptor levels were determined. Platelet pre-activation surface marker levels were found to be significantly higher in patients than controls for CD63 (p=0,001) and CD62P (p=0,004). Upon activation with ADP, all activation marker levels were found higher in controls compared to patients. The differences were significant for CD63 (p=0,006), CD62P (p=0,024) and PAC-1 (p<0,001). After TRAP activation, patients showed lower levels of activation marker expression than controls. Differences were statistically significant for CD63 (p<0,001), CD62P (p<0,001) and PAC-1 levels (p<0,001). There were no significant difference between non-bleeding and bleeding patients for all parameters. CD63 (p=0,009) and CD62P levels were higher before activation in bleeding patients than controls. After ADP and TRAP stimulation CD63, CD62P, PAC-1 levels were lower in bleeding group than controls (p<0,001). No difference was found between platelet count in bleeding and non-bleeding patients. PCT and MPV levels were significantly lower in patients than controls whereas PDW levels were found higher in patients than controls (p<0,001). This study shows that, flow cytometric analysis of platelets surface activation markers may help predict bleeding tendency in thrombocytopenic patients.