Effect of Erythropoietin on Platelet Function and Glycoprotein Expression in Patients with MDS.

Aim: We decide to study the effect of erythropoietin on the platelet function and glycoproteins expression in patients (pts) with myelodysplastic syndrome (MDS). All patients suffered from primary MDS but none of them received any special treatment. From our study pts that suffered from diseases or they were receiving medication that affect the function of platelets were excluded. Furthermore pts with platelet count<50,000/μl were excluded also because we were unable to check the aggregation of platelets.

Material: 41 subjects were studied, 15 normal subject (10 men and 5 women mean age 66,6±14 years old)and 26 pts (17 men and 9 women with mean age70,9±7,4 years old) suffered from all types of MDS according to FAB criteria (9 with RA, 3 with RARS, 7 RAEB, 4 with CMML and 3 with RAEB-t). We divided them in 2 groups: 1^st - 7 Pts receiving human recombinant erythropoietin (rEPO) with mean dose 30.000 iu subcutaneous weekly and 2^nd - 19 without rEPO.

Methods.

1- The platelet function was studied in Platelet Ionized Calcium Aggregometer (PICA) using Ristocetin, ADP, Collagen and Adrenalin as stimulators.

2- The expression of platelet glycoproteins (GPIb, IX, IIb, IIIa and P-selectin) was studied using the flow cytometry and special monoclonal antibodies.

This way the percentage of glycoprotein expressed in platelet membrane and MFI were estimated. We performed the statistical analysis of our results using the t-test with common standard deviation..

Results: our results concerning the aggregation test and flow cytometry are presented in tables 1,2 and 3. From the study of our results we can see that

1. while the decrease of aggregation between the patients under EPO and normal subjects is statistically non significant (p<0.1)the decrease of the corresponding values between the pts that did not received EPO and normal subjects was statistically very significant for all stimulators (p <0,001).

2. pts under EPO show an important increase of platelet expressing GPIIb percentage grater than the expressed percentage of patients without EPO (60% vs. 46,1% correspondingly, p<0.001).

3. The difference of expressed MFI was not statistically significant.

Conclusion: The findings of our study show us that erythropoietin improves the function of platelets in patients with MDS, probably through the increase of platelet percentage which express glycoproteins.

Table 1

Comparison of the mean value of aggregation between the groups

Table 2 Comparison of the mean values of the platelets expressing corresponding glycoproteins percentage between the groups

Table 3 Comparison of the mean value of MFI between the groups

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