Correlation between the cord vitamin D levels and regulatory T cells in newborn infants.

Vitamin D is important for calcium homeostasis, muscle, and bone health. It has also immunomodulatory capacities in vivo and in vitro. Regulatory T cells (Treg) have been found to suppress a number of T cell-mediated immune disorders, including allergic responses and autoimmune diseases. This study aimed to investigate the correlation between 25-hydroxyvitamin D (25(OH)D) levels and the regulatory T cells in cord blood. The study group is comprised of 101 full-term newborn infants. Umbilical cord 25(OH)D levels and number and percentage of T lymphocyte, T helper, and Treg cells were measured. Infants were grouped according to 25-hydroxyvitamin D levels (25(OH)D <12 ng/ml and 25(OH)D >12 ng/ml) (converting factor of 25OHD level into SI unit, 2.6). Severe vitamin D deficiency (25(OH)D <12 ng/ml) was observed in 32% of the infants. There was no significant correlation between 25-hydroxyvitamin D levels and T cell number and percentages. There were also no significant differences in white blood cell, total lymphocyte count, T helper, and Treg cell percentage and number between groups. These results suggest that the serum level of 25-hydroxyvitamin D is not crucially involved in the correlation between vitamin D status and T cell regulation in cord blood.

Human bone marrow mesenchymal cells express NG2: possible increase in discriminative ability of flow cytometry during mesenchymal stromal cell identification.

BACKGROUND AIMS: Mesenchymal stromal cells (MSC) exhibit non-specific hematopoietic cell and/or stromal cell markers (e.g. CD73, CD105 and CD166) that have been used to identify MSC by flow cytometry. Because a neural glial antigen, NG2 (a progenitor cell marker in the central nervous system), is expressed by several tissue cells originating in the mesenchyme but not hematopoietic cells, it might be useful for isolating and identifying MSC. We investigated NG2 expression on culture-expanded MSC by flow cytometry. METHODS: Human bone marrow (BM) samples taken from 12 donors were cultured for MSC to be used in up to nine serial passages. Using flow cytometry, the neural glial antigen NG2 and commonly used MSC markers CD73, CD105 and CD166, were analyzed on the surface of culture-expanded MSC. The multipotential differentiation of the MSC was examined by adipogenic and osteogenic induction. RESULTS: The percentage of cells positive for NG2 was similar to the percentages of cells positive for CD73, CD105 and CD166 in all passages of BM samples. The mean fluorescent intensities of NG2 did not change with culture passage. The MSC was successfully differentiated into adipogenic and osteogenic lines. The cells showed no karyotypic abnormalities. CONCLUSIONS: NG2 seems to be a promising marker for investigating the biology of MSC.

Platelet P-selectin expression in patients with sickle cell disease who undergo apheresis.

Activated platelets have been identified in patients with sickle cell disease. However, the association of platelet P-selectin expression and automated red cell exchange procedures in these patients is not well known. We hypothesized that altered whole platelet P-selectin expression is associated with automated red cell exchange. Flow cytometric quantification of platelet P-selectin expression was carried out in 23 patients with sickle cell disease before and after automated red cell exchange. P-selectin expression was quantified as a binding index for platelet P-selectin (the percentage of positive platelets multiplied by the mean fluorescence of positive platelets). The patients were divided into two groups: individuals with painful vaso-occlusive crises (four women and five men; group 1) and those in a steady state (six women and eight men; group 2). The 33 exchange procedures were evaluated prospectively and used acid-citrate-dextrose A solution (whole blood to anticoagulant ratio = 14:1). Platelet P-selectin expression did not significantly change after automated red cell exchange. Clinical factors such as the volume of replacement fluid and the citrate infusion rate did not correlate with postapheresis platelet P-selectin expression. In addition, the association of platelet P-selectin expression and automated red cell exchange was independent of other laboratory factors (hematocrit level, hemoglobin S level, platelet count, and nitric oxide level). Finally, the difference between the study groups regarding platelet P-selectin expression before and after apheresis was insignificant. In conclusion, automated red cell exchange procedures do not induce platelet P-selectin expression in patients with sickle cell disease in the steady state or in vaso-occlusive crisis.

Flow cytometric evaluation of circulating endothelial cells: a new protocol for identifying endothelial cells at several stages of differentiation.

Several factors may influence the analysis of endothelial cells (ECs) by flow cytometry: separation of mononuclear cell, washing and centrifugation steps, panel of monoclonal antibodies, and the lack of standardization of gating technique. Therefore, the reliable quantification of ECs remains a technical challenge. The purpose of this study is to define a new flow cytometric protocol to characterize and quantitate ECs. In previous investigations, increased numbers of circulating ECs have been found in sickle cell disease. The patients with sickle cell disease might provide useful material for the study. We performed flow cytometry on whole blood from 20 normal controls and 31 patients with sickle cell disease (20 patients with steady-state disease and 11 patients with vaso-occlusive crises) using a lyse/no-wash procedure, specific and nonspecific antibody combinations (CD146, CD144, CD34, and CD117), and broad gating. This protocol produced much higher values for the number of circulating ECs (a mean of 2,396.55 +/- 658.37 ECs/mL in controls vs 6,709.60 +/- 1,772.32 ECs/mL in the steady-state group, or 18,213.50 +/- 8,451 in the vaso-occlusive crises group, P < 0.001 for both), and also showed variable EC size and granularity, which may reflect activated, or early release ECs. This novel protocol performed comparably in terms of reproducibility, reliability, and dilution linearity with a previously described protocol. This approach has significant advantages for the characterization and quantitation ECs compatible with the pathophysiology. Using the specific antibodies, CD146 and CD144, together may give more informative EC data than the general approach used.

The apoptosis of blood polymorphonuclear leukocytes in sickle cell disease.

BACKGROUND: The apoptosis of human polymorphonuclear leukocytes (PMNs) in patients with sickle cell disease (SCD) is not well understood. The goal of this study was to examine the apoptosis of PMNs in patients with SCD and in controls. METHODS: Flow cytometric quantitation of PMN apoptosis was performed in 17 patients during and after sickle cell vasoocclusive crisis and in 17 healthy volunteers. Plasma nitric oxide concentrations were also measured in patients with SCD. RESULTS: The mean of annexin-V and annexin-V/PI staining (early and late apoptotic cells) increased to a greater degree in patients with SCD than in healthy controls for patients with SCD during and after vasoocclusive crisis. The mean of PI staining showing dead cells was higher only in patients after SCD crisis than in healthy controls. In the SCD groups during and after vasoocclusive crisis, there was no difference between PMN apoptosis levels. Furthermore, plasma nitric oxide concentrations were not correlated with PMN apoptosis. CONCLUSIONS: There was an evidence that the alteration of blood PMN apoptosis could contribute to the pathogenetic mechanisms of vasoocclusion in patients with SCD. This can be attributed to the effects of numerous inflammatory mediators rather than simply the effects of nitric oxide.