Immunology and Infection
Published: July 28th, 2016
This protocol describes the quick enrichment of leukocytes from small blood samples for a subsequent specific determination of the halogenating peroxidase activity within the cells. The method can be applied to human and non-human material and may contribute to the evaluation of new inflammatory markers.
In this paper a protocol for the quick and standardized enrichment of leukocytes from small whole blood samples is described. This procedure is based on the hypotonic lysis of erythrocytes and can be applied to human samples as well as to blood of non-human origin. The small initial sample volume of about 50 to 100 µl makes this method applicable to recurrent blood sampling from small laboratory animals. Moreover, leukocyte enrichment is achieved within minutes and with low material efforts regarding chemicals and instrumentation, making this method applicable in multiple laboratory environments.
Standardized purification of leukocytes is combined with a highly selective staining method to evaluate halogenating peroxidase activity of the heme peroxidases, myeloperoxidase (MPO) and eosinophil peroxidase (EPO), i.e., the formation of hypochlorous and hypobromous acid (HOCl and HOBr). While MPO is strongly expressed in neutrophils, the most abundant immune cell type in human blood as well as in monocytes, the related enzyme EPO is exclusively expressed in eosinophils. The halogenating activity of these enzymes is addressed by using the almost HOCl- and HOBr-specific dye aminophenyl fluorescein (APF) and the primary peroxidase substrate hydrogen peroxide. Upon subsequent flow cytometry analysis all peroxidase-positive cells (neutrophils, monocytes, eosinophils) are distinguishable and their halogenating peroxidase activity can be quantified. Since APF staining may be combined with the application of cell surface markers, this protocol can be extended to specifically address leukocyte sub-fractions. The method is applicable to detect HOCl and HOBr production both in human and in rodent leukocytes.
Given the widely and diversely discussed immunological role of these enzymatic products in chronic inflammatory diseases, this protocol may contribute to a better understanding of the immunological relevance of leukocyte-derived heme peroxidases.
Polymorphonuclear leukocytes (PMNs, also called granulocytes) and monocytes represent important cellular components of the innate immune system in the blood1,2. They contribute to the primary defense against pathogens as well as to the activation of the acquired immune system and the initiation of a systemic inflammatory response2-4. Yet especially neutrophils, the most abundant type of granulocytes, and monocytes also significantly contribute to the regulation and termination of acute inflammatory events5. Therefore these cells may also play an important role in chronic inflammatory diseases like rheumatoid arthritis6,7. In....
All human blood samples were obtained from healthy volunteers, and the applied leukocyte enrichment protocol follows the guidelines of ethics commission of the Medical Faculty of the University of Leipzig. The experiments with rat blood were approved by the responsible local ethical committee (Landesdirektion Sachsen, Referat 24), according to the German guidelines on animal care and use.
1. Experimental Setup
NOTE: As the hypotonic lysis procedure for the depletion o.......
As reported previously the method described above turned out to be applicable both to human and to non-human material32. Moreover as shown for mice with asthmatic symptoms the APF staining may be a suitable tool to detect differences in the systemic pro-inflammatory status. Therefore in a subsequent study we used this protocol to repeatedly evaluate the halogenating activity of MPO (and EPO) in female Dark Agouti rats with pristane-induced arthritis (PIA). A representa.......
As neutrophils are the most abundant leukocytes in human blood the isolation of peroxidase-positive cells often only focuses on these cells and includes a separation of neutrophils from other leukocytes by density gradient centrifugation38. Yet as neutrophils are much less abundant in murine blood samples39 for the latter more complicated methods have to be used40. Moreover both methods also lead to the removal of peroxidase-positive monocytes from the samples and, due to the need of larg.......
This work was made possible by funding from the German Federal Ministry of Education and Research (BMBF, 1315883) as well as by the Sächsische Aufbaubank (SAB) project 100116526 from a funding of the European Regional Development Fund (ERDF).....
|15 ml centrifugation tubes
|1.5 ml sample tubes
|Pipettes for volumes up to 5 ml
|We are using Eppendorf Resarch plus pipettes with adjustable volumes in the range 1-10 µl, 10-100µl, 100-1000 µl an 500-5000µl
|laminar flow bench
|Thermo Electron Corperation
|Bender & Hobein AG
|Vortex Genie 2
|Kendro Laboratory Products
|The centrifuge should be able to be used at 450x g
|The centrifuge should be able to be used at 400x g
|Settings: 37 °C, 95% humidity, 5 % CO2 content
|Cary 50 bio
|A spectrum between 200 and 300 nm has to be recorded. Thus quartz cuvettes have to be applied
|BD Facs Calibur
|Any flow cytometer can be used which is equiped with a laser suitable for the excitation of fluorescein (e.g 488 nm argon laser)
|Phosphate buffered saline (PBS)
|sterile solution, ready to use
|tablets for solving in 200 ml millipore water
|Hanks balanced salt solution (HBSS) with Ca(2+)
|970 mg/100 ml, carefully check and adjust the pH value to 7.4
|Solid pellets. For a 1M solution solve 4 g/100 ml Millipore water
|5 mg/ml solution (11.81 mM) in methyl acetate, aliquotes of e.g. 100 µl should be prepared and stored at -20 °C
|This 30% stock solution corresponds to a concentration of about 8.8 M. Further dilutions have to be freshly prepared in distilled water immediately prior to use and quantified by absorbance measurements
|4-aminobenzoic acid hydrazide (4-ABAH)
|A first stock solution of 1 M should be prepared in DMSO a second one of 100 mM by 1:10 dilution in HBSS
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