ABSTRACT
Early thrombocytopenia is a common hematological abnormality in sick neonates. Here, we examined the relationship between early thrombocytopenia in neonates and parameters associated with thrombopoiesis to identify predictive factors at birth. Two hundred and forty-four neonates admitted to the neonatal intensive care unit were divided into thrombocytopenic (n = 55, 23%) and non-thrombocytopenic (n = 189, 77%) groups based on platelet counts, which were monitored within 72 h of birth. Immature platelet fraction (IPF) and platelet count at birth were determined simultaneously soon after phlebotomy with an automated hematology analyzer. Megakaryocytes and their precursors positive for CD41 in peripheral blood were examined at birth by flow cytometry. The thrombocytopenic group showed significantly higher IPF percentage and lower percentage of CD41+ mononuclear cells (MNCs) than did the non-thrombocytopenic group (P < 0.01). Moreover, the percentage of CD41+ MNCs significantly differentiated neonates with platelet counts >150 x 10(3)/microL at birth and nadir platelet count <150 x 10(3)/microL over the clinical course from neonates without thrombocytopenia. These observations suggest that the percentage of CD41+ MNCs at birth and IPF percentage are useful predictors of early thrombocytopenia in the majority of sick neonates.
Subject(s)
Blood Platelets/cytology , Megakaryocytes/cytology , Platelet Membrane Glycoprotein IIb/metabolism , Thrombocytopenia, Neonatal Alloimmune/blood , Age of Onset , Blood Platelets/metabolism , Flow Cytometry , Gestational Age , Humans , Infant, Newborn , Infant, Premature/blood , Megakaryocytes/metabolism , Platelet Count , Risk Factors , Thrombocytopenia, Neonatal Alloimmune/epidemiologyABSTRACT
CD4+ 25+ regulatory T cells (Tregs) play a role in controlling the development and progression of autoimmunity. The transcription factors Foxp3 and NFATC2 (NFAT1) play key roles in regulating the development and function of Tregs. The present study examined the involvement of Tregs in the pathophysiology of autoimmune neutropenia in children. Tregs were analysed by flow cytometry, based on the expressions of CD4, CD25, and intracellular Foxp3. The expressions of FOXP3 and NFATC2 mRNA in the CD4+ 25+ cells were determined by quantitative real-time polymerase chain reaction. The percentage of CD4+ 25(high) Tregs in patients with autoimmune neutropenia was significantly lower than that in age-matched healthy subjects. The intracellular expression of Foxp3 of CD4+ 25+ cells in patients similarly decreased in comparison to that in healthy subjects. The expression of FOXP3 and NFATC2 mRNA of CD4+ 25+ cells in patients also significantly decreased in comparison to that in healthy subjects. These results suggest that the deficiency of Tregs might thus play an important role in the immunopathophysiology of autoimmune neutropenia in children.
