scholarly journals The relationship between released soluble FceRI-alpha and its cell surface density on human basophils

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0245942
Author(s):  
Donald MacGlashan
Keyword(s):  
Molecular Weight ◽  
Flow Cytometry ◽  
Cell Surface ◽  
Surface Density ◽  
Alpha Subunit ◽  
Constant Amount ◽  
Western Blots ◽  
Ige Mediated ◽  
The Relationship ◽  
Human Basophils

Background The IgE-mediated activation of mast cells and basophils results in the secretion of many substances, including the release of FceRI-alpha subunit. This released alpha subunit can bind IgE and it may act as a down-regulator of subsequent IgE-dependent reactions. However, previous studies do not observe loss of the mass of FceRI-alpha associated with the cells, at least not for human basophils. This study was designed to understand the basis for the discordant observations. Methods Purified human basophils were stimulated with multiple activating secretagogues and supernatants were examined for histamine and released FceRI-alpha. In addition, cell surface IgE densities (occupied and unoccupied) were measured by flow cytometry and total cellular content of mature and immature FceRI-alpha determined with Western blots. Results Released FceRI-alpha, on average, represented 7% of the total surface FceRI before the reaction. The molecular weight of the soluble FceRI-alpha was approximately 54 kD, larger than immature subunit and somewhat smaller than surface subunit. In addition, 1) release ceased long before internalized FceRI-alpha was processed, 2) release was insensitive to Bafilomycin A, 3) release was independent of the starting density of FceRI and 4) release occurred more effectively with non-IgE-dependent stimuli, FMLP or C5a. Conclusions There appears to be relatively constant amount of nearly mature FceRI-alpha that is susceptible to secretion events induced by any form of stimulation. The amount, on average, represents about 7% of the mature form of FceRI-alpha.

The Role of Urokinase Receptor (uPAR) In Efferocytosis: uPAR Engulfs Apoptotic Cells via a Phosphatidylserine Pathway Mediated by Plasma High Molecular Weight Kininogen

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 929-929 ◽  
Author(s):  
Aizhen Yang ◽  
Jihong Dai ◽  
Raymond B. Birge ◽  
Yi Wu
Keyword(s):  
Molecular Weight ◽  
Flow Cytometry ◽  
Cell Surface ◽  
High Molecular Weight ◽  
Apoptotic Cell ◽  
Annexin V ◽  
Apoptotic Cells ◽  
High Molecular Weight Kininogen ◽  
Viable Cells

Abstract Abstract 929 Phagocytosis of apoptotic cells by phagocytes, also known as efferocytosis, is essential for maintaining normal tissue homeostasis and regulating immune responses. Defects in rapid clearance of apoptotic cells lead to the release of immunogenic cellular contents, which may cause tissue damage and autoimmune disease. Phagocytic receptors differentiate apoptotic cells from viable cells by recognizing ‘don't eat- or eat-me’ signals on the cell surface. Recently, we and others have reported the role of uPAR in mediating efferocytosis. In this study, we examined the mechanism by which uPAR recognizes and internalizes apoptotic cells. By flow cytometry-based in vivo and in vitro phagocytosis assay, we found that in knockout mice the lack of uPAR expression on macrophages decreased their apoptotic cell engulfing activity by >35%. Conversely, soluble uPAR and polyclonal anti-uPAR antibodies (Ab) suppressed the internalization of apoptotic cells by macrophages. However, there was no defect in uPAR-/- macrophage uptake of viable cells, suggesting that uPAR plays a specific role in phagocytosis of apoptotic cells. We established a HEK 293 cell line expressing human full-length uPAR (293-uPAR). In these cells, uPAR-mediated phagocytosis of apoptotic cells was completely blocked by annexin V in the presence of calcium. The effect of annexin V was not observed in the absence of calcium, indicating that uPAR internalizes apoptotic cells through a phosphatidylserine pathway. We also found that uPAR-mediated uptake of apoptotic cells was completely prevented under serum-free conditions. To identify plasma proteins that may opsonize the uPAR function, we used immunodepletion method to test three known uPAR-binding proteins, vitronectin, uPA and high molecular weight kininogen (HK). Depletion of HK from serum by a polyclonal anti-HK Ab significantly reduced the engulfment of apoptotic cells by either macrophages or 293-uPAR cells in a co-culture system. In contrast, depletion of vitronectin or uPA from serum had little effect. uPAR is a GPI-anchored protein. Upon sucrose gradient ultracentrifugation, the majority of uPAR molecules were co-localized with membrane-bound HK in lipid rafts. The binding capacity of HK to apoptotic cell surface was further analyzed by flow cytometry. Phycoerythrin-labeled HK bound to apoptotic cells in a concentration-dependent manner, saturating at 300 nM. In contrast, HK did not bind to viable cells at concentrations up to 1200 nM. It is known that HK is a key component of the plasma contact system and that apoptotic cells potentiate factor Xa formation. Our new findings of the uPAR-HK-phosphatidylserine axis in efferocytosis suggest that this pathway may modulate the coagulation cascade on the surface of apoptotic cells. This pathway may also play a role in the pathogenesis of autoimmune and thrombotic disease. Disclosures: No relevant conflicts of interest to declare.

Component resolved diagnostics in peanut sensitized children with and without a history of clinical reaction

2020 ◽  
Vol 41 (5) ◽  
pp. 336-340
Author(s):  
Yasmin Hamzavi Abedi ◽  
Cristina P. Sison ◽  
Punita Ponda
Keyword(s):  
Retrospective Chart Review ◽  
Clinical History ◽  
Specific Ige ◽  
Exact Test ◽  
Ara H 1 ◽  
Sige Level ◽  
History Of ◽  
Laboratory Procedures ◽  
Ige Mediated ◽  
The Relationship

Background: Serum Peanut-specific-IgE (PN-sIgE) and peanut-component-resolved-diagnostics (CRD) are often ordered simultaneously in the evaluation for peanut allergy. Results often guide the plans for peanut oral challenge. However, the clinical utility of CRD at different total PN-sIgE levels is unclear. A commonly used predefined CRD Ara h2 cutoff value in the literature predicting probability of peanut challenge outcomes is 0.35kUA/L. Objective: To examine the utility of CRD in patients with and without a history of clinical reactivity to peanut (PN). Methods: This was a retrospective chart review of 196 children with PN-sIgE and CRD testing, of which, 98 patients had a clinical history of an IgE-mediated reaction when exposed to PN and 98 did not. The Fisher's exact test was used to assess the relationship between CRD and PN-sIgE at different cutoff levels, McNemar test and Gwet’s approach (AC1 statistic) were used to examine agreement between CRD and PN-sIgE, and logistic regression was used to assess differences in the findings between patients with and without reaction history. Results: Ara h 1, 2, 3, or 9 (ARAH) levels ≤0.35 kUA/L were significantly associated with PN-sIgE levels <2 kUA/L rather than ≥2 kUA/L (p < 0.0001). When the ARAH threshold was increased to 1 kUA/L and 2 kUA/L, these thresholds were still significantly associated with PN-sIgE levels of <2, <5, and <14 kUA/L. These findings were not significantly different in patients with and without a history of clinical reactivity. Conclusion: ARAH values correlated with PN-sIgE. Regardless of clinical history, ARAH levels are unlikely to be below 0.35, 1, or 2 kUA/L if the PN-sIgE level is >2 kUA/L. Thus, if possible, practitioners should consider PN-sIgE rather than automatically ordering CRD with PN-sIgE every time. Laboratory procedures that allow automatically and reflexively adding CRD when the PN-sIgE level is ≤5 kUA/L can be helpful. However, further studies are needed in subjects with challenge-proven PN allergy.

Glycoconjugates on the surface of spores of the pathogenic fungus Phytophthora cinnamomi studied using fluorescence and electron microscopy and flow cytometry

1990 ◽  
Vol 36 (3) ◽  
pp. 183-192 ◽  
Author(s):  
A. R. Hardham ◽  
E. Suzaki
Keyword(s):  
Flow Cytometry ◽  
Plasma Membrane ◽  
Cell Surface ◽  
Phytophthora Cinnamomi ◽  
Pathogenic Fungus ◽  
Fluorescein Isothiocyanate ◽  
Pathogenic Fungi ◽  
Surface Flow ◽  
Soybean Agglutinin ◽  
Binding Material

Glycoconjugates on the surface of zoospores and cysts of the pathogenic fungus Phytophthora cinnamomi have been studied using fluorescein isothiocyanate labelled lectins for fluorescence microscopy and flow cytometry, and ferritin- and gold-labelled lectins for ultrastructural analysis. Of the five lectins used, only concanavalin A (ConA) binds to the surface of the zoospores, including the flagella and water expulsion vacuole. This suggests that of accessible saccharides, glucosyl or mannosyl residues predominate on the outer surface of the zoospore plasma membrane. Early in encystment, a system of flat disc-like cisternae, which underlie the zoospore plasma membrane, vesiculate. These and other small peripheral vesicles quickly disappear. After the induction of encystment, ConA is no longer localised close to the plasma membrane but binds to material loosely associated with the cell surface. Quantitative measurements by flow cytometry indicate that the ConA-binding material is gradually lost from the cell surface. The cyst wall is weakly labelled, but the site of germ tube emergence stains intensely. During the first 2 min after the induction of encystment, material that binds soybean agglutinin, Helix pommatia agglutinin, and peanut agglutinin appears on the surface of the fungal cells. The distribution of this material, rich in galactosyl or N-acetyl-D-galactosaminosyl residues, is initially patchy, but by 5 min the material evenly coats most of the cell surface. Labelling of zoospores in which intracellular sites are accessible indicates that the soybean agglutinin binding material is stored in vesicles that lie beneath the plasma membrane. Quantitation of soybean agglutinin labelling shows that maximum binding occurs 2–3 min after the induction of encystment. Key words: cell surface, flow cytometry, lectins, pathogenic fungi, Phytophthora cinnamomi.

scholarly journals Slow Human Immunodeficiency Virus (HIV) Infectivity Correlated with Low HIV Coreceptor Levels

2001 ◽  
Vol 8 (5) ◽  
pp. 932-936 ◽  
Author(s):  
Cynthia L. Bristow
Keyword(s):  
Human Immunodeficiency Virus ◽  
Cell Surface ◽  
Chemokine Receptors ◽  
Surface Density ◽  
Human Leukocyte ◽  
Absolute Number ◽  
Mononuclear Phagocytes ◽  
Leukocyte Elastase ◽  
Immunodeficiency Virus

ABSTRACT The absolute number of CD4+ lymphocytes in blood is prognostic for disease progression, yet the cell surface density of CD4 receptors or chemokine receptors on a single cell has not previously been found to be predictive of human immunodeficiency virus (HIV) infectivity outcome. It has recently been shown that human leukocyte elastase (HLE) and its ligand α1 proteinase inhibitor (α1PI; α1 antitrypsin) act as HIV fusion cofactors. The present study shows that decreased HIV infectivity is significantly correlated with decreased cell surface density of HLE but not with decreased CD4 nor chemokine receptors. In vitro HIV infectivity outcome in this study was predicted by the surface density of HLE on mononuclear phagocytes but not on lymphocytes. The set point HLE surface density was in part determined by α1PI. Decreased circulating α1PI was correlated with increased cell surface HLE and with increased HIV infectivity. The correlation of HIV infectivity outcome with surface HLE and circulating α1PI supports the utility of these HIV cofactors in diagnostic analysis and therapeutic intervention.

Detection of inducible nitric oxide synthase inSchistosoma japonicumandS. mansoni

2004 ◽  
Vol 78 (1) ◽  
pp. 47-50 ◽  
Author(s):  
X.-C. Long ◽  
M. Bahgat ◽  
K. Chlichlia ◽  
A. Ruppel ◽  
Y.-L. Li
Keyword(s):  
Nitric Oxide ◽  
Molecular Weight ◽  
Inducible Nitric Oxide Synthase ◽  
Mouse Liver ◽  
Apparent Molecular Weight ◽  
Western Blots ◽  
Oxide Synthase ◽  
Host Tissues ◽  
Inducible Nitric Oxide

AbstractSchistosoma japonicumandS. mansoniwere tested for reactivity with an anti-inducible nitric oxide (iNOS) antibody and the distribution of iNOS was studied by immunofluorescent tests in different stages of the parasites. Reactivity was associated with the tegument in both larval schistosomes (sporocysts and cercariae) and eggs. With adult worms, the majority of the immunofluorescence was predominantly subtegumental inS. japonicumand parenchymal inS. mansoni. Fluorescence was also observed in host tissues (snails and mouse liver). In Western blots, the enzyme ofS. japonicumhad an apparent molecular weight of about 210 kDa. The possible role of worm and host iNOS in the parasite–host interrelation remains to be clarified.

Metabolic expression of thiol-derivatized sialic acids on the cell surface and their quantitative estimation by flow cytometry

2006 ◽  
Vol 1 (4) ◽  
pp. 1840-1851 ◽  
Author(s):  
Srinivasa-Gopalan Sampathkumar ◽  
Mark B Jones ◽  
Kevin J Yarema
Keyword(s):  
Flow Cytometry ◽  
Cell Surface ◽  
Quantitative Estimation ◽  
Sialic Acids
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