Evaluation of Plasma Platelet Microparticles in Thrombotic Thrombocytopenic Purpura

Background: Platelet microparticles (PMPs) have a procoagulant activity about 50-100 times greater than active platelets due to high expression of negatively charged phospholipids on their surfaces. In this study, we evaluated microparticle immunophenotyping and also plasma PMPs level in patients with Thrombotic Thrombocytopenic Purpura (TTP) in Southern Iran.

Method: We had two study groups: 15 TTP patients and 15 healthy control group and PMPs from platelet concentrate (PC) at the 5^th day of storage. Microparticles were prepared in two steps, by low and high centrifugation followed by size confirmation via 'Dynamic Light Scattering (DLS)' Zetasizer. Immunophenotyping of PMPs was done via flow cytometry, using a FACS Calibur flow cytometer (BD, USA). PMPs counts were obtained using Partec-cyflow and Polysciences Microbeads (1 micron in diameter). Results were analyzed using FlowJo 7.6 (Treestar, USA) and Partec FlowMax software.

Results: Our results showed that the majority of microparticles in TTP patients and normal individuals were PMPs and also demonstrated that the plasma PMPs level in TTP patients was higher than the normal control group (P-value<0.001).

Conclusion: It seems that elevated PMPs level in TTP patients could be related to thrombotic events. Nevertheless, more studies are needed to confirm these results.