Transient pseudothrombocytopenia in a neonate: transmission of a maternal EDTA-dependent anticoagulant.

EDTA-dependent pseudothrombocytopenia (PTCP) is characterised by a low platelet count caused by autoantibodies in the serum reacting with EDTA-anticoagulated blood. EDTA-dependent PTCP is caused by a factor that retains EDTA anticoagulation activity in the serum. We report here that a neonate from a mother with PTCP presented with transient low platelet counts when EDTA was used as an anticoagulant. To confirm the transmission of a maternal serum factor to the neonate, we examined to add the maternal serum into the normal blood. Platelet count decreased significantly after adding maternal serum. Clumped platelets were also observed in the smears of mixed samples.

Decreased expression in nuclear factor-κB essential modulator due to a novel splice-site mutation causes X-linked ectodermal dysplasia with immunodeficiency.

X-linked ectodermal dysplasia with immunodeficiency (XL-ED-ID) is caused by hypomorphic mutations in NEMO, which encodes nuclear factor-kappaB (NF-κB) essential modulator. We identified a novel mutation, 769-1 G>C, at the splicing acceptor site of exon 7 in NEMO in a Japanese patient with XL-ED-ID. Although various abnormally spliced NEMO messenger RNAs (mRNAs) were observed, a small amount of wild-type (WT) mRNA was also identified. Decreased NEMO protein expression was detected in various lineages of leukocytes. Although one abnormally spliced NEMO protein showed residual NF-κB transcription activity, it did not seem to exert a dominant-negative effect against WT-NEMO activity. CD4(+) T cell proliferation was impaired in response to measles and mumps, but not rubella. These results were consistent with the clinical and laboratory findings of the patient, suggesting the functional importance of NEMO against specific viral infections. The 769-1 G>C mutation is responsible for decreased WT-NEMO protein expression, resulting in the development of XL-ED-ID.

Successful treatment of Kasabach-Merritt syndrome with vincristine and diagnosis of the hemangioma using three-dimensional imaging.

Kasabach-Merritt syndrome is a life-threatening congenital disorder characterized by an enlarging hemangioma, thrombocytopenia, and consumption coagulopathy. We report the case of a one-month male infant who presented with a large cutaneous tumor in his right axilla with ecchymosis, thrombocytopenia, and chronic consumption coagulopathy. Three-dimensional computed tomography was useful for accurate diagnosis of the cutaneous tumor and for determining the precise vascular constitution of the hemangioma, suggesting the efficacy of this method for diagnosing Kasabach-Merritt syndrome. Although administration of a corticosteroid was not effective, additional administration of vincristine resulted in the reversal of thrombocytopenia and coagulopathy with reduction of the hemangioma.

Significance of immature platelet fraction and CD41-positive cells at birth in early onset neonatal thrombocytopenia.

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.

Short-term culture of umbilical cord blood-derived CD34 cells enhances engraftment into NOD/SCID mice through increased CXCR4 expression.

Human umbilical cord blood (CB) has been used successfully in stem cell transplantation. A subpopulation of CD34(+) cells expresses chemokine receptor CXCR4 which is critical for bone marrow engraftment in human hematopoietic stem cells. Here, we demonstrate the effect of short-term culture on CXCR4 expression on umbilical CB-derived CD34(+) cells and subsequent engraftment capability in nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice. Surface CXCR4 expression on CD34(+) cells increased after incubating the cells in medium alone for 2 h; this effect was blocked by the addition of AMD3100. No difference in CXCR4 mRNA expression was noted after incubating CD34(+) cells in culture for 2 h, although these cells showed significantly increased transmigrational activity toward SDF-1 and homing activity in NOD/SCID mice. Furthermore, cultured human CD34(+) cells showed improved engraftment into the bone marrow of NOD/SCID mice compared to noncultured or AMD3100-treated CD34(+) cells. These observations suggest that increased cell surface expression of CXCR4 on CD34(+) cells improved the engraftment of human umbilical CB cells into bone marrow through enhanced homing activity.

Reciprocal expression of Bmi1 and Mel-18 is associated with functioning of primitive hematopoietic cells.

OBJECTIVE: The Polycomb-group (PcG) genes regulate global gene expression in many biological processes, including hematopoiesis, by manipulating specific target genes. It is known that various PcG genes regulate self-renewal of hematopoietic stem cells (HSCs). Here we have shown that the reciprocal expression of PcG proteins regulates self-renewal and differentiation of HSCs. METHODS: We used murine and human bone marrow cells and evaluated the reciprocal expression of PcG proteins on the basis of their respective intranuclear distributions. PcG-gene expression in HSCs was knocked down by small interfering RNAs. The function of each gene in HSCs was analyzed in vitro and in vivo. RESULTS: Cells were either Bmi1-positive or Mel-18-positive. The Bmi1-positive cells contained very little amounts of Mel-18 and vice versa. The bmi1-knockdown marrow cells did not show HSC function, while the mel-18-knockdown marrow cells showed increased stem cell function. Results of the analysis on human cells were similar to those observed in case of murine cells. In a clinical investigation, transplantation using sources with a low Bmi1 to Mel-18 ratio was associated with early hematopoietic recovery. CONCLUSION: Reciprocal expression of Bmi1 and Mel-18 regulated HSC function. Here, we observed that expression of the PcG genes-bmi1 and mel-18-is correlated with self-renewal and differentiation of HSCs. Thus, it was suggested that the balance between Bmi1 and Mel-18 regulates self-renewal of HSCs.