Platelet microparticles in immune thrombocytopenic purpura in pediatrics.

Immune thrombocytopenic purpura (ITP) is one of the most common hemorrhagic disorders in childhood. Platelet microparticles (PMPs) arise with platelet activation with procoagulant activity. Elevated PMP levels in adult ITP were reported to be thrombogenic in certain settings. However, their clinical significance in pediatric ITP was not studied. The aims of this study were to assess PMP levels in ITP in children and adolescents, and its correlation with clinical status and bleeding score. The study included 40 ITP patients (20 acute aged 9 +/- 2.19 years and 20 chronic aged 10.8 +/- 4.7 years) randomly selected from the Hematology Clinic, Children's Hospital, Ain Shams University, Cairo, Egypt, and 30 sex- and age-matched healthy controls aged 9 +/- 3.28 years. Patients were subjected to detailed history, assessment of bleeding score, complete hemogram, cytological bone marrow examination, and PMP quantification in peripheral blood by flow cytometry. Acute ITP patients had significant increase in PMPs, PMP/platelet count, and PMP percent compared to controls (P = .002, P < .0001, P < .0001, respectively) and compared to chronic ITP patients (P < .0001, P < .0001, P < .0001, respectively). PMPs were significantly decreased in chronic ITP patients compared to controls (P = .001), but PMP/platelet and PMP percent showed highly significant increase in chronic ITP (P < .0001). No correlation was evident between PMP levels and platelet count in either group (P > .05). Neither higher bleeding score nor thrombotic manifestations were observed in the studied ITP patients with high PMP levels. Elevated PMP levels may be protective against severe bleeding events in pediatric ITP. The role of PMP studies in deciding the management plan of childhood and adolescent ITP needs further evaluation.