Evaluation of humoral pattern detection performance of Mindray BC-6000PLUS blood analyzer based on WS/T 662-2020.

BACKGROUND: Manual microscopic examination is the gold standard of humoral cell count test. However, it has some limitations and cannot fully meet clinical needs. Compared with the manual method, the automatic blood cell analyzer has the advantages of a high degree of automation, minimal error, high speed, high precision, and easy standardization. This study intends to verify the detection performance of the body fluid model of the Mindray BC-6000PLUS automatic hematology analyzer. METHODS: This study was performed in accordance with the International Committee for Standardization in Haematology (ICSH) Hematology Analyzer Evaluation Guide (version 2014) and the requirements of WS/T662-2020 "Clinical humoral examination technique". The humoral white blood cell-body fluid (WBC-BF), humoral red blood cell-body fluid (RBC-BF), monocyte (MN), polymorphonuclear (PMN) were measured to verify the performance indicators of the instrument, including background counting, intra-batch precision, accuracy, carrying contamination rate, and linear range. Referring to the WS/T514-2017 (Establishment and verification of detection capability for clinical laboratory measurement procedures), the limit of blank (LoB) and limit of detection (LoD) values of WBC-BF and RBC-BF in the humoral mode of the instrument were established. RESULTS: The blank count of WBC-BF and RBC-BF, and contamination of Mindray BC-6000PLUS analyzer were zero; the coefficient of variation (CV) of intra-batch precision at different levels of each item was less than 10%. There was a high correlation between instrument test results and manual microscopic examination results (r>0.95). The linear range of the instrument was wide, and the linear verification parameters was good (R2>0.999). The LoB value and LoD value of WBC-BF established by the instrument were 0×109/L and 0.004×109/L, respectively. The LoB value and LoD value of the RBC-BF established by the instrument were 0×1012/L and 0.004×1012/L, respectively. The lower detection limits of WBC-BF and RBC-BF were set as 0.004×109/L and 0.004×1012/L, respectively. CONCLUSIONS: All performance indicators of the Mindray BC-6000PLUS automatic blood analyzer met the requirements of the manufacturer's criteria. This instrument can fulfill the requirement of body fluid sample routine test in clinical practice.

Glucocorticoid Induces Hepatic Steatosis by Inhibiting Activating Transcription Factor 3 (ATF3)/S100A9 Protein Signaling in Granulocytic Myeloid-derived Suppressor Cells.

Glucocorticoids (GCs) used as inflammation suppressors have harmful side effects, including induction of hepatic steatosis. The underlying mechanisms of GC-promoted dysregulation of lipid metabolism, however, are not fully understood. GCs could facilitate the accumulation of myeloid-derived suppressor cells (MDSC) in the liver of animals, and the potential role of MDSCs in GC-induced hepatic steatosis was therefore investigated in this study. We demonstrated that granulocytic (G)-MDSC accumulation mediated the effects of GCs on the fatty liver, in which activating transcription factor 3 (ATF3)/S100A9 signaling plays an important role. ATF3-deficient mice developed hepatic steatosis and displayed expansion of G-MDSCs in the liver and multiple immune organs, which shared high similarity with the phenotype observed in GC-treated wild-type littermates. Adoptive transfer of GC-induced or ATF3-deficient G-MDSCs promoted lipid accumulation in the liver, whereas depletion of G-MDSCs alleviated these effects. Mechanistic studies showed that in MDSCs, ATF3 was transrepressed by the GC receptor GR through direct binding to the negative GR-response element. S100A9 is the major transcriptional target of ATF3 in G-MDSCs. Silencing S100A9 clearly alleviated G-MDSCs expansion and hepatic steatosis caused by ATF3 deficiency or GC treatment. Our study uncovers an important role of G-MDSCs in GC-induced hepatic steatosis, in which ATF3 may have potential therapeutic implications.

Myeloid-derived suppressor cells in major depression patients suppress T-cell responses through the production of reactive oxygen species.

Major depression is closely associated with immune dysregulation. Myeloid-derived suppressor cells (MDSCs) are an important suppressor of immune responses. The aim of this study was to evaluate the possible role of MDSCs in major depression patients. We collected peripheral blood mononuclear cells (PBMCs) from 25 major depression patients and 25 healthy donors, and the frequency of MDSCs was determined by flow cytometric analysis. The proportion of MDSCs was increased in the peripheral blood of major depression patients, when compared with healthy controls. Further functional studies revealed that MDSCs from depression patients suppressed T cell function potently. We examined the reactive oxygen species (ROS) content in MDSCs from 6 major depression patients and 6 healthy controls. The ROS content in depression derived MDSCs was significantly elevated, when compared with those from healthy controls. We also examined the arginase activity and NO content in 5 major depression patients and 5 healthy controls, respectively. But no significant changes were detected between two groups. Administration of a ROS inhibitor completely abrogated the suppressive effect of MDSCs on T cells. In conclusion, our study revealed that MDSCs from depression patients suppress T cell reponses in ROS-dependent manner.

Norepinephrine-induced myeloid-derived suppressor cells block T-cell responses via generation of reactive oxygen species.

Increased numbers of myeloid-derived suppressor cells (MDSCs) are often observed in various pathological and physiological conditions. However, the interactions between neurotransmitters and MDSCs have not been elucidated. In this study, we studied whether norepinephrine (NE), a neurotransmitter, could affect the differentiation of human MDSCs in vitro. Flow cytometric analysis showed that treatment with 20 µM NE significantly enhanced the expansion of MDSCs. The NE-generated MDSCs suppressed the T-cells proliferation, depending on the production of reactive oxygen species (ROS). Moreover, the expansion of MDSCs induced by NE resulted in a dramatic induction of nicotinamide adenine dinucleotide phosphate oxidase subunit P47(phox). Addition of the ROS inhibitor catalase into the MDSCs/T-cell co-culture system partly abrogated the suppressive effects of MDSCs on T-cell proliferation. In summary, our data have shown that NE enhanced the expansion of human MDSCs in vitro, providing important insights into the novel roles of neurotransmitters in the regulation of myeloid cell differentiation and function.

Cross talk between histone deacetylase 4 and STAT6 in the transcriptional regulation of arginase 1 during mouse dendritic cell differentiation.

l-Arginine and l-arginine-metabolizing enzymes play important roles in the biology of some types of myeloid cells, including macrophage and myeloid-derived suppressor cells. In this study, we found evidence that arginase 1 (Arg1) is required for the differentiation of mouse dendritic cells (DCs). Expression of Arg1 was robustly induced during monocyte-derived DC differentiation. Ectopic expression of Arg1 significantly promoted monocytic DC differentiation in a granulocyte-macrophage colony-stimulating factor culture system and also facilitated the differentiation of CD8α(+) conventional DCs in the presence of Flt3 ligand. Knockdown of Arg1 reversed these effects. Mechanistic studies showed that the induced expression of Arg1 in differentiating DCs was caused by enhanced recruitment of histone deacetylase 4 (HDAC4) to the Arg1 promoter region, which led to a reduction in the acetylation of both the histone 3 and STAT6 proteins and subsequent transcriptional activation of Arg1. Further investigation identified a novel STAT6 binding site within the Arg1 promoter that mediated its regulation by STAT6 and HDAC4. These observations suggest that the cross talk between HDAC4 and STAT6 is an important regulatory mechanism of Arg1 transcription in DCs. Moreover, overexpression of Arg1 clearly abrogated the ability of HDAC inhibitors to suppress DC differentiation. In conclusion, we show that Arg1 is a novel regulator of myeloid DC differentiation.

Ribavirin enhances myeloid-derived suppressor cell differentiation through CXCL9/10 downregulation.

Elevation of myeloid-derived suppressor cells (MDSCs) was observed in some viral infectious diseases. In this study, we studied whether ribavirin, a widely used clinical antiviral drug, could impact the differentiation of human MDSCs in vitro. Flow cytometric analysis showed that ribavirin treatment (5-20 µg/ml) significantly enhanced the differentiation of monocytic MDSCs in a dose-dependent manner. The ribavirin-generated MDSCs were immune-suppressive toward autologous T cells. The mRNA expression of some cytokines was further examined by quantitative reverse transcription polymerase chain reaction. We observed a significant down-regulation of chemokine (C-X-C motif) ligand 9 (CXCL9) and CXCL10 mRNA in ribavirin-generated MDSCs, when compared with control. Peripheral blood mononuclear cells from clinical chronic hepatitis C patients subjected to ribavirin therapy also displayed a similar suppression in CXCL9/10 mRNA expression. Administration of recombinant CXCL9/10 proteins clearly counteracted the effect of ribavirin on MDSCs. In summary, this study showed that ribavirin enhanced human MDSCs differentiation in vitro, which may be attribute to the down-regulation of CXCL9/10 expression.