Altered Activated-phenotypic And Immune-phenotypic Features Of Peripheral Blood Platelets In Patients With Myelodysplastic Syndromes

Objective:The purpose of this study was to evaluate the changes of platelet activated-phenotype and immune-phenotype in MDS and its correlation with bleeding and infection events,and further to explore the effect of altered phenotypic features on bleeding and infection in MDS patients.Methods:In this study,29 cases MDS diagnosed in the Department of Hematology,General Hospital of Tianjin Medical University,and 22 normal controls were enrolled.According to IPSS-R score,hypomethylating agents(HMAs)history and platelets transfusion history,MDS patients were divided into the lower-risk group and the higher-risk group,the untreated group and the treated group,the before-transfusion group and the after-transfusion group.Multiparameter flow cytometry(MFC)was used to detect the expression of platelet phenotype in peripheral blood of patients with MDS and normal controls,including Forward scatter(FSC),Side scatter(SSC),CD41 a,activated-phenotypes CD62 p and CD63 and immune-phenotypes CD154 and TLR4.Then the correlation between activated-phenotype and bleeding events,and the correlation between immune-phenotype and infection risk were analyzed.Results:1.Changes of platelet basic characteristics in peripheral blood of patients with MDS : there was no significant difference in FSC-MFI and SSC-MFI of platelets between MDS groups and normal control group.CD41a-MFI of platelets in the lower-risk group,the higher-risk group,the treated group,the before-transfusion group and the after-transfusion group were significantly lower than that in the normal control group(P=0.009;P=0.005;P=0.008;P=0.006;P=0.031),and there was no significant difference among the other groups.2.The changes of platelet activated-phenotype in peripheral blood of MDS : there was no significant difference in the CD62p+PLT%,the CD63+PLT%,the CD62p-MFI and the CD63-MFI between MDS patients in each group and normal control group when platelets were not activated(P>0.05).After activated by adenosine diphosphate,the CD63-MFI of platelets in the higher-risk group,the untreated group and the before-transfusion group were significantly lower than that in the normal control group(P=0.017;P=0.026;P=0.019).The CD63+PLT% in the higher-risk group was significantly lower than that in the normal control group(P=0.036).The CD62p+PLT%,the CD63+PLT%,the CD62p-MFI and the CD63-MFI in platelets were different but no significant difference among the other groups.3.The changes of platelet immune-phenotype in peripheral blood of MDS : the CD154-MFI and the TLR4-MFI of platelets in the higher-risk group were significantly lower than that in the normal control group(P=0.024;P=0.034).The CD154+PLT%,the TLR4+PLT%,the CD154-MFI and the TLR4-MFI of platelets in the untreated group were significantly lower than those in the normal control group(P=0.001;P=0.020;P<0.001;P=0.001),and the CD154+PLT% and the TLR4+PLT% in the untreated group were significantly lower than those in the treated group(P=0.002;P=0.041).Platelet transfusion had no significant effect on platelet immune function in MDS patients.4.Correlations between altered platelet phenotypes in peripheral blood of MDS and clinical indexs:(1)the CD62p+PLT%,the CD63+PLT%,the CD62p-MFI and the CD63-MFI of platelets were not significantly correlated with bleeding events,there was a significant negative correlation between platelet count(PLT)and bleeding events(r=0.646,P < 0.001).(2)the CD62p+PLT% and the CD62p-MFI of platelets were negatively correlated with white blood cell count(WBC)(r=-0.496,P=0.006;r=-0.498,P=0.006),negatively correlated with absolute neutrophil count(ANC)(r=-0.512,P=-0.005;r=-0.442,P=0.016).(3)the CD62p+PLT% and the CD62p-MFI of platelets were positively correlated with prothrombin time(PT)(r=0.409,P =0.028;r=0.489,P=0.007),negatively correlated with fibrinogen(FIB)(r=-0.415,P=0.025;r=-0.510,P=0.005),and D-dimer(DD)(r=-0.547,P=0.002;r=-0.601,P=0.001).In addition,the CD62p-MFI of platelets was also positively correlated with prothrombin international standardized ratio(PT-INR)(r=0.402,P=0.03).(4)The TLR4+PLT%,the CD154+PLT%,the TLR4-MFI and the CD154-MFI were not significantly correlated with the severity of infection(P > 0.05).Conclusion:1.There was no difference in platelet FSC and SSC between MDS patients and healthy donors,suggesting that there may be no significant changes in platelet volume and cytoplasm in MDS patients.In addition,the expression of CD41 a was decreased in some MDS patients,including the lower-risk group,the higher-risk group,the treated group,the before-transfusion group and the after-transfusion group,this may be related to the abnormal development of megakaryocytes or platelets in MDS patients.2.There was no difference in expression of platelet activated-phenotype between MDS patients and healthy donors when platelets were not activated.The expression of platelet activated-phenotype in peripheral blood of some MDS patients was lower than that of healthy donors,mainly in MDS patients with higher IPSS-R score,before HMAs treatment and before platelet transfusions.It is suggested that new diagnosed and higher IPSS-R score patients are more vulnerable to impaired platelet activation function,and HMAs treatment and platelet transfusions may have the effect in improving platelet activation function.3.The platelet immune-phenotype in some MDS patients was lower than that in healthy donors,mainly in MDS patients with higher-risk and before HMAs treatment.There was no difference in platelet immune-phenotype between MDS patients and healthy donors before and after platelet transfusion.It is suggested that new diagnosed and higher IPSS-R score patients are more vulnerable to impaired platelet immune function,and HMAs treatment may improve platelet immune function,but platelet transfusion can not significantly improve the platelet immune function phenotype.4.There was no significant correlation between the expression of platelet CD62 p and CD63 and bleeding events in MDS patients,suggesting that PLT was still the most important factor to forecast bleeding.The CD62p+PLT% and the CD62p-MFI are negatively correlated with WBC and ANC,the expression of platelet CD154 and TLR4 is not correlated with infection,which suggested that the severity of infection in human body will promote platelet activation,release cytokines,and recruit white blood cells,finally promote inflammatory reaction,so neutrophil counts and its functions are still the main factors affecting the risk of infection in MDS patients and the immunomodulatory function of platelets is not very important in anti-infection process of MDS patients.The CD62p+PLT% and the CD62p-MFI were negatively correlated with FIB and DD,and was positively correlated with PT,the level of CD62p-MFI was also positively correlated with PT-INR,suggesting that platelet activation can promote the coagulation cascade reaction,that hypercoagulability may inhibit platelet activation,and that poor coagulation function may promote platelet activation.