Platelet Microparticles in Pediatric Patients with Leukemia and Solid Tumors

Abstract

ny cells, including platelets, endothelial cells, leukocytes, and erythrocytes, shed small fragments of their plasma membranes into the circulation. There is increasing evidence that these submicron fragments, termed microparticles, have important physiological roles. Platelet microparticles are the most abundant microparticles in the bloodstream constituting approximately 70% to 90% of circulating microparticles. PMPs promote platelet and leukocyte adhesion, platelets, monocytes and endothelial cells activation. PMPs have a role in cell-to-cell communication, Inflammation, Angiogenesis and Cell Proliferation. Many studies reported that the level of platelet microparticles appears to be affected by cancer. Several studies have also showed associations between platelet-derived microparticles and tumor progression. We aimed to study the effect of childhood cancer on the level of plasma microparticles and its relation to remission (response) status and also to study the effect of the level of plasma microparticles on the bleeding or thrombotic complications of childhood cancer patients. The study was a short follow up case control study including 25 newly diagnosed patients prior to start of treatment protocol; they were divided into 3 groups according to the type of malignancy. The 1st group included 10 patients with acute lymphoblastic leukemia (ALL), the 2nd group 10 patients with acute myeloid leukemia (AML) and the 3rd group 5 patients with neuroblastoma. Initial clinical presentation, staging, risk stratification, serum LDH were recorded. All patients received induction Phase of chemotherapy, enrolled ALL patients received CCG 1991 protocol, AML patients received Modified MRC 12 protocol and patients with neuroblastoma received POG 9340. After assessment of BM on day 28 in patients with ALL, with peripheral blood picture recovery in AML and after 5 cycles induction in patients with neuroblastoma, all leukemia patients should have BM blast less than 5 % in second evaluation, neuroblastoma patients should have at least 50% reduction in size of the primary mass with disappearance of metastatic sites. Level of platelets microparticles were done by flowcytometry before chemotherapy and after induction phase (complete remission or very good partial response(. No significant difference in median initial or post-induction PMPs between patients with ALL (1.48 (0.62 – 1.87); 2.6 (1.84 – 4.11), AML 1.48 (0.88 – 2.25), 1.84 (1.03 – 2.90)) neuroblastoma (1.77 (0.75 – 1.77); 1.76 (1.75 – 2.89)), P=0.595 and 0.232 respectively. There was no significant difference between pre and post induction PMPs in patients with ALL (P=0.401), AML (P=0.482); and a significant rise in PMP was found in patients