Flow cytometry "Ogata score" for the diagnosis of myelodysplastic syndromes in a real-life setting. A Latin American experience.

INTRODUCTION: Flow cytometry (FC) is a helpful tool for the diagnosis of myelodysplastic syndrome (MDS). Different FC score systems have been developed. The "Ogata score" is a simple diagnostic score that has been validated having a sensitivity of 69% and a specificity of 92% in low-risk MDS. We aimed to study the feasibility and the utility of the "Ogata score" for the diagnosis of MDS among Latin America (LA) Laboratories. METHODS: This is a case and control study conducted in LA institutions members of Grupo Latinoamericano de Mielodisplasia (GLAM). A total of 146 MDS patients and 57 control patients were included. "Ogata score" was calculated. RESULTS: The sensitivity of "Ogata score" was 75.6% (95% CI, 66.8-81.3), specificity was 91.2% (95% CI, 79.7-96.7), PPV was 95.6% (95% CI, 88.5-98.3), and NPV was 65.4% (95% CI, 49.1-71.9). In low/intermediate-1 IPSS patients group, the sensitivity was 70.1% (95% CI, 60.2-78.2), specificity was 91.2% (CI-95%, 79.7-96.7), PPV was 94.2% (95% CI, 86.4-97.8), and NPV was 62.1% (95% CI, 53.0-78.7). In the group of patients "without MDS specific markers" (patients without ring sideroblasts, blast excess, or chromosomal abnormalities), the sensitivity was 66.7% (CI-95%, 55.8-76.0), specificity was 91.2% (95% CI, 79.7-96.7), PPV was 92.3% (95% CI, 82.2-97.1), and NPV was 63.5% (95% CI, 51.9-73.5). CONCLUSIONS: The diagnostic power found in this study was similar to the reported by Della-Porta et al. Also in LA, the analysis was made in modern equipment with acquisition of at least 100 000 events which permits a good reproducibility of the results.

Quantifying loss of CD34+ cells collected by apheresis after processing for freezing and post-thaw.

INTRODUCTION: CD34(+) cells collected for autologous bone marrow transplantation (BMT) are usually quantified in the apheresis product after collection, but the necessity to repeat these measures post-thaw is controversial. METHODS: We examined the loss of CD34(+) cells after collection, preparation for freezing and post-thaw in apheresis products collected for BMT. RESULTS: Median number of CD34(+) cells collected per unit was 1.61×10(6)/kg, viability: 97-100%. This number decreased to 1.38×10(6)/kg, viability: 96-100% before freezing and was 1.17×10(6)/kg post-thaw. Viability decreased to 86-98%. The relative loss of viable PBHPC showed an inverse correlation with the ratio "CD34(+) cells/total nucleated cells" (r=-0.45; p=<0.0005). This relative loss was largest in patients with Hodgkin's lymphoma. CONCLUSION: Cryopreservation and thawing of PBHPCs in leukapheresis products provokes a small but significant stem cell loss. So, quantification of viable CD34(+) cells post-thaw is important, especially in poorly mobilizing patients. Besides, the ratio "CD34(+) cells/total nucleated cells" after leukapheresis is an important parameter for prediction of neutrophil recovery after BMT.

Viability of umbilical cord blood mononuclear cell subsets until 96 hours after collection.

BACKGROUND: Umbilical cord blood (UCB) is a good source of hematopoietic stem cells for transplantation and cell therapy. In 2006, the Brazilian Public Network of Cord Blood Banks was founded; however, because our country is large, logistic problems could hamper the collection of numerous samples. Our aim was to evaluate the viability of several UCB cell subsets until 96 hours after collection, to examine whether this delay would be acceptable for processing and freezing the samples. STUDY DESIGN AND METHODS: Two experiments were performed: in the first one, volume reduction of the UCB units was carried out before analysis. In the second one, analysis was carried out with no previous manipulation. Samples were stored at room temperature and one aliquot was taken daily for analysis. We examined CD34+ cell, B-cell precursor, mature B and T lymphocyte, monocyte, granulocyte, and mesenchymal stem cell (MSCs) concentrations. RESULTS: Thirty-six UCB units were analyzed. CD34+ cells and mature T lymphocytes increased (viability 99%). Mature B lymphocytes and MSCs decreased, maintaining viability. Granulocytes decreased with loss of viability. Monocytes and immature B lymphocytes remained stable. Clonogenic assays showed a decrease in colony-forming unit (CFU) number in UCB units stored for 96 hours. CONCLUSION: UCB manipulation did not influence cell viability. All cell subsets remained viable until 96 hours after collection. CD34+ cells and T lymphocytes increased, probably due to the loss of other subsets. CFU growth during the period analyzed and confirmed stem cell functionality, despite the decrease at 96 hours. Results demonstrated that UCB units could probably be processed up to 96 hours after collection.

Lipopolysaccharide treatment reduces rat platelet aggregation independent of intracellular reactive-oxygen species generation.

High production of reactive-oxygen species (ROS) by blood cells is involved in damage of the vascular endothelium and multiple organ dysfunction in sepsis. However, little is known about the intraplatelet ROS production in sepsis and its consequences on platelet reactivity. In this study, we evaluated whether the treatment of rats with lipopolysaccharide (LPS) affects platelet aggregation through intraplatelet ROS generation. Rats were injected with LPS (1 mg/kg, i.p.), and at 2 to 72 h thereafter, adenosine diphosphate (ADP) (3-10 µM) induced platelet aggregation was evaluated. Production of ROS in platelets was measured by flow cytometry using 2',7'-dichlorofluorescein diacetate (DCFH-DA). Treatment of rats with LPS time-dependently inhibited ADP-induced platelet aggregation within 72 h. The inhibitory effect of LPS on platelet aggregation was further increased when the platelets were incubated with polyethylene glycol-superoxide dismutase (PEG-SOD; 30 U/mL), polyethylene glycol-catalase (PEG-CAT; 1000 U/mL) or the NADPH oxidase inhibitor diphenyleneiodonium (DPI; 10 µM). The ROS production in non-stimulated platelets did not differ between control and LPS-treated rats. However, in ADP-activated platelets, generation of ROS was increased by 3.0- and 7.0-fold, as evaluated at 8 and 48 h after LPS injection, respectively. This increased ROS production was significantly reduced when platelets were incubated in vitro with DPI, PEG-SOD or PEG-CAT. In contrast, treatment of rats with N-acetylcysteine (150 mg/kg, i.p.) significantly reduced the inhibitory effect of LPS on platelet aggregation, and prevented the increased ROS production by in vivo LPS. Our results indicate that the increased intraplatelet ROS production does not contribute to the inhibitory effect of LPS on platelet aggregation; however, the maintenance of redox balance in LPS-treated rats is fundamental to restore the normal platelet response in these animals.