Redistribution of platelet membrane glycoprotein iv and release of intracellular α-granule thrombospondin in patients with chronic myelogenous leukemia

Summary The redistribution of platelet membrane glycoprotein IV (GPIV) and the release of intracellular α-granule thrombospondin (TSP) were examined and the inhibition of β-thromboglobulin (β-TG) and platelet factor 4 (PF4) in patients with chronic myelogenous leukemia (CML) was observed and quantitation of β-TG and PF4 in sera was conducted. GPIV in inactive platelet from CML was 36080± 17010 molecules/platelet as compared with 13190±4810 from the controls (P< 0.01). No abnormality was found in the distribution of platelet membrane GPI_b and GPII_b/III,(P> 0.05). The GPIV redistribution on active platelet membrane induced thrombin (IU/ml) from CML and healthy donors was 44320 ±32310 and 22800± 12700 molecules/platelet respectively (P< 0.01). The difference in the release of intracellular α-granule TSP between CML and the control group was not found (P> 0.05). There was no direct correlation between GPIV expression and TSP binding after platelet activation. The high levels of β-TG and PF4 in sera inhibited release of intracellular α-granule TSPin vitro. These results indicate that the abnormality of platelet membrane GPIV is a common marker in CML, therefore the specific increase of platelet GPIV in patients with CML may be a useful tool for the diagnosis and monitoring of the platelet dysfunction. The release of internal TSP pools is hindered by either β-TG or PF4 in sera. This project was supported by the National Natural Science Foundation of China (No. 39370322).