Yuri Takagi

Morphological definition of CD71 positive reticulocytes by various staining techniques and electron microscopy compared to reticulocytes detected by an automated hematology analyzer

BACKGROUND The enumeration of peripheral blood reticulocytes plays an important part in clinical hematology. Although reticulocyte enumeration is currently performed with visible dyes such as New Methylene Blue (NMB), fluorescent dyes, or anti-CD71 (transferrin receptor) antibody, it has not been demonstrated whether the reticulocytes detected in each method are the same or not. METHODS We prepared the reticulocyte rich fraction with density gradient centrifugation, stained with both anti-CD71 and Sysmexs fluorescent stain RET SEARCH (II), and detected the cells by both confocal laser scanning microscopy and flow cytometry. We also stained the reticulocyte rich fraction and the CD71+ reticulocytes with NMB and compared them by microscopy. We also observed the CD71+ reticulocytes by electron microscopy. RESULTS Almost all CD71+ reticulocytes were intensely stained with both NMB and RET SEARCH (II). These cells were therefore classified as highly immature reticulocytes. During the stages of reticulocyte maturation, the expression of CD71 antigen decreased prior to the reduction of the reticular structures. The electron microscopic observation showed that CD71+ reticulocytes had some typical morphological characteristics found in highly immature reticulocytes. CONCLUSIONS The CD71+ reticulocytes consisted of highly immature reticulocytes and were not equal to the reticulocytes defined with NMB or RET SEARCH (II).

Rapid Discrimination of Gram-Positive and Gram-Negative Bacteria in Liquid Samples by Using NaOH-Sodium Dodecyl Sulfate Solution and Flow Cytometry

Background For precise diagnosis of urinary tract infections (UTI), and selection of the appropriate prescriptions for their treatment, we explored a simple and rapid method of discriminating gram-positive and gram-negative bacteria in liquid samples. Methodology/Principal Findings We employed the NaOH-sodium dodecyl sulfate (SDS) solution conventionally used for plasmid extraction from Escherichia coli and the automated urine particle analyzer UF-1000i (Sysmex Corporation) for our novel method. The NaOH-SDS solution was used to determine differences in the cell wall structures between gram-positive and gram-negative bacteria, since the tolerance to such chemicals reflects the thickness and structural differences of bacterial cell walls. The UF-1000i instrument was used as a quantitative bacterial counter. We found that gram-negative bacteria, including E. coli, in liquid culture could easily be lysed by direct addition of equal volumes of NaOH-SDS solution. In contrast, Enterococcus faecalis, which is a gram-positive bacterium, could not be completely lysed by the solution. We then optimized the reaction time of the NaOH-SDS treatment at room temperature by using 3 gram-positive and 4 gram-negative bacterial strains and determined that the optimum reaction time was 5 min. Finally, in order to evaluate the generalizability of this method, we treated 8 gram-positive strains and 8 gram-negative strains, or 4 gram-positive and 4 gram-negative strains incubated in voluntary urine from healthy volunteers in the same way and demonstrated that all the gram-positive bacteria were discriminated quantitatively from gram negative bacteria using this method. Conclusions/Significance Using our new method, we could easily discriminate gram-positive and gram-negative bacteria in liquid culture media within 10 min. This simple and rapid method may be useful for determining the treatment course of patients with UTIs, especially for those without a prior history of UTIs. The method may be easily applied in order to obtain additional information for clinical prescriptions from bacteriuria.

Deferasirox Reduces Oxidative Stress in Patients With Transfusion Dependency

Background Iron chelation therapy is useful against the over-accumulation of iron and is expected to reduce oxidative stress resulting from the Fenton reaction and Haber-Weiss reaction. We monitored oxidative status and serum ferritin levels after in vivo administration of deferasirox (DFS) and studied the in vitro effects of iron chelators on neutrophil function. Methods Nine patients suffering from transfusion dependency were recruited for this study, and derivatives of reactive oxygen metabolite (dROM) tests to detect serum hydroperoxide levels were evaluated in addition to serum ferritin levels. Human neutrophil reactive oxygen species (ROS) production was determined with flow cytometry. Results Ferritin levels decreased after DFS treatment (P = 0.068), and a significant reduction in dROM levels was measured (P = 0.031). Fifty microM DFS significantly inhibited ROS production induced by fMLP in vitro (P < 0.0001), and tended to inhibit that induced by PMA. On the other hand, deferioxamine failed to inhibit ROS production even at high concentrations. Conclusions In vivo administration of DFS resulted in the reduction of oxidative stress, and this effect was considered to depend not only on a reduction in iron storage but also on the ability of DFS to inhibit neutrophil ROS production in vitro at clinically relevant plasma levels. Further studies are needed to examine the effects of iron chelators.

Heme‐related molecules induce rapid production of neutrophil extracellular traps

Pulmonary endothelial cell damages caused by neutrophil overactivation could result in acute lung injuries including transfusion‐related acute lung injury (TRALI). We previously reported that heme‐related molecules derived from hemolysis induced the production of reactive oxygen species from neutrophils. Recently, neutrophil extracellular traps (NETs) have been demonstrated to associate with the onset of TRALI.

Morphological and flow-cytometric analysis of haemin-induced human neutrophil activation: implications for transfusion-related acute lung injury

BACKGROUND Transfusion-related acute lung injury (TRALI) is associated with vascular endothelial cell injury following neutrophil activation. Recently, it has been suggested that haem-related molecules induce activation of neutrophils and that erythrocyte-derived substances contained in blood preparations are involved in TRALI. We observed the morphological effects and reactive oxygen species (ROS) production of haem-related molecules and investigated the effects of signal transduction inhibitors on haem-induced neutrophil activation. MATERIALS AND METHODS The polymorphonuclear cell fraction was isolated and stimulated using a control stimulant, PMA or fMLP, or by haem-related molecules, haemin, ferric citrate, or protoporphyrin IX. After stimulation, neutrophil was analysed using electron microscopy, a flowcytometer (FCM) and confocal laser scanning microscope to determine the fluorescent intensity of aminophenyl fluorescein (to detect ROS). RESULTS In FCM analysis, haemin and protoporphyrin IX, both of which have a porphyrin ring, induced ROS production in neutrophils. Ferric citrate, which has no porphyrin ring, did not induce neutrophil activation. Haemin alone induced ROS production at relatively high concentrations, whereas low-level fMLP acted as an agonist in the presence of low concentrations of haemin. Haem-related molecules induced ROS production in neutrophil granules through signal transduction in a way similar to PMA. However, in electron microscopy studies, haemin stimulated neutrophils showed minute process at their surface and did not show the vacuolation observable following stimulation with PMA or fMLP. DISCUSSION We suggest that low concentrations of haem-related molecules with porphyrin rings in the presence of other stimulating agent are important for ROS production and possibly the onset of TRALI. The ROS production induced by these molecules is dependent on a signal transduction pathway in a way similar to PMA.

Accuracy of a New Platelet Count System (PLT-F) Depends on the Staining Property of Its Reagents

Background Platelet count is essential for the diagnosis and management of hemostasis abnormalities. Although existing platelet count methods installed in common hematology analyzers can correctly count platelets in normal blood samples, they tend to miscount platelets in some abnormal samples. The newly developed PLT-F channel in the XN-Series hematology analyzer (Sysmex) has been reported to be a reliable platelet count system, even in abnormal samples. However, how the PLT-F platelet counting system achieves such accuracy has not been described in scientific articles. Methods Isolated platelets, erythrocytes, and fragmented erythrocytes were examined using an automated hematology analyzer. The samples were labeled by combining PLT-F reagents and anti-CD62p, CD63, Grp75, Calreticulin, CD41, or CD61 antibody, and analyzed using confocal laser scanning microscopy or flow cytometry. Results The PLT-F system correctly discriminated platelets in erythrocytes. Its reagents strongly stained some intraplatelet organelles labeled with anti-Grp75, but only faintly stained the plasma membrane of both platelets and erythrocytes. Microscopic observation and flow cytometric examination revealed that all of these strongly stained cells were also labeled with platelet-specific anti-CD41 and anti-CD61 antibodies. Conclusions This study revealed that the staining property of the PLT-F reagents, by which platelets and fragmented erythrocytes are clearly distinguished, contributes to the platelet-counting accuracy of the PLT-F system.

Non-activated T and B lymphocytes become morphologically distinguishable after detergent treatment

T and B lymphocytes are difficult to distinguish morphologically even with electron microscopy, and antibodies are generally used to make the distinction. A specific reagent, consisting of nonionic and cationic detergents, is used for leukocyte differentiation using the Sysmex automated blood analyzer. This reagent increases cell membrane porosity and enables the introduction of fluorescent dye into leukocytes. In this study, we investigated the effect of this specific detergent on the morphology of T and B lymphocytes. T and B lymphocytes were obtained by density gradient centrifugation and magnetic cell sorting, with a minimum of 90% isolation efficiency. T and B lymphocytes were then treated with the specific detergent and fluorescent dye, and their distribution was analyzed based on side scatter and fluorescence intensity using general‐purpose flow cytometry (FCM). Fluorescent images were observed using a confocal laser scanning microscope (CLSM), cellular inner structures using a transmission electron microscopy (TEM), and cell surfaces using a scanning electron microscope (SEM). The ratio of cholesterol to total lipid in cell membranes of B and T lymphocytes was measured using a fluorescent assay kit. The distribution of fluorescence intensity was different between T and B lymphocyte clusters, according to the FCM analysis. CLSM observations revealed that the fluorescent dye mainly stained cytoplasmic organelles. FCM, TEM, and SEM observations revealed that B lymphocytes are more likely to lose surface antigens and intracellular organelles than T lymphocytes, which allows the visual distinction between T and B lymphocytes. The ratio of cholesterol to total lipid in T lymphocyte membranes had tendency higher than that in B lymphocyte membranes. In this study, we demonstrate that cells with differences in cell membrane cholesterol amounts, such as B and T lymphocytes could be identified using an inexpensive detergent, as an alternative to costly antibodies.

Comparison of optical data from flow cytometry and microscopy of leukocytes after exposure to specific reagents

Flow cytometry and microscopy are equally important in cell analysis. However, few reports have compared the optical data (cell size, internal complexity and fluorescent signal) from flow cytometry and microscopy. In this study, we compared the scattergram from XN-series, a flow cytometry based hematology analyzer with microscopic images of similarly treated leukocytes, and investigated the correlation between the appearance in the scattergram and cell size, internal complexity and fluorescence intensity. Healthy human peripheral blood was analyzed using the XN analyzer. For microscopic comparison, five types of leukocytes (monocytes, lymphocytes, basophils, neutrophils and eosinophils) were isolated from the peripheral blood by centrifugation and magnetic cell sorting, treated with a specific reagent and analyzed using electron microscopy, laser microscopy and confocal laser microscopy. Cell size, residual internal structures and fluorescence intensity correlated with intensity of forward-scattering, side scattering and fluorescent light. In this study, optical data from a clinically used hematology analyzer was clarified using microscopic images.

Investigation of morphological changes for the discrimination of nucleated red blood cells and other leukocytes in Sysmex XN hematology analyzer scattergrams using transmission electron microscopy

Background The WNR channel of the XN-Series automated hematology analyzer (Sysmex) counts white blood cells (WBCs) and simultaneously performs a differential counting of basophils and nucleated red blood cells (NRBCs). The detection process involves exposing the cells to WNR-specific reagents containing an acidic detergent and a fluorescent dye and measuring the intensity of the forward scattered light (FSC) and side fluorescence light (SFL). Method We treated isolated peripheral WBCs and NRBCs with specific reagents and assessed the morphological changes in NRBCs and each leukocyte type using transmission electron microscopy (TEM). Results The results from a flow cytometer (FCM) showed that, after exposure to the reagents, basophils appeared on the highest FSC and SFL areas compared to other leukocytes on the WNR scattergram. Owing to the hemolysis of reticulocytes and erythrocytes, NRBCs that survived the reagent treatment could be distinguished by their lower intensity than those of the other leukocytes on the WNR scattergram. We investigated the significance of the relationship between the TEM and FCM results after the reagent treatment. Conclusion We confirmed that the WNR channel differentiates the blood cells on the WNR scattergram based on differences in the amount of residual cytoplasm and nucleic acids.