Dec 13, 2022

Public workspaceWhole blood assay-Scrub typhus for flow cytometer

DOI
dx.doi.org/10.17504/protocols.io.5jyl8jd2dg2w/v1
  • 1Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand;
  • 2Mahidol-Oxford Tropical Medicine Research Unit, Bangkok, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand;
  • 3Department of Veterinary Medicine, United States Army Medical Directorate, Armed Forces Research Institute of Medical Sciences (USAMD-AFRIMS), Bangkok, Thailand
Manutsanun Inthawong
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DOI: dx.doi.org/10.17504/protocols.io.5jyl8jd2dg2w/v1
Protocol Citation: Manutsanun Inthawong 2022. Whole blood assay-Scrub typhus for flow cytometer. protocols.io https://dx.doi.org/10.17504/protocols.io.5jyl8jd2dg2w/v1
License: This is an open access protocol distributed under the terms of the Creative Commons Attribution License,  which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Protocol status: Working
We use this protocol and it's working
Created: December 13, 2022
Last Modified: December 13, 2022
Protocol Integer ID: 73904
Funders Acknowledgement:
Mahidol-Oxford Tropical Medicine Research Unit is supported by the Wellcome Trust
Grant ID: WT100174/Z/12/Z
Abstract
This is an optimized new whole blood assay for studying scrub typhus-specific cellular responses specifically suited for work in remote areas. This assay is based on stimulation with a whole cell O. tsutsugamushi antigen (HI-WCA-OT) in order to study broad antigen-specific cellular immune responses.
We provide the preparation method (Heat inactivation) and the adequate concentration for the antigen (109 of O. tsutsugamushi DNA copies/ml) to obtain optimal measureable specific cellular immune responses in whole blood samples for use in a Biosafety level (BSL) 2 laboratory.



Procedure to perform the optimised WBA for patients with scrub typhus at a field site laboratory
Before starring
Solutions to be made up
R0·490 ml RPMI 1640 (without glutamine) ·5 ml 10000 U/ml penicillin/streptomycin from aliquot. ·5 ml 200 mM L-Glutamine from aliquot. ·Label “R0” and write date, initials, and write PS and LG lot numbers on the bottle. Store at 4°C and replace after 1 month or if any concern about sterility PBS ·Made with PBS tablets from SIGMA, and dH2O.1 tablet in 100ml water.

Protocol materials
ReagenteBioscience™ Brefeldin A Solution (1000X)Thermo FisherCatalog #00-4506-51
Step 5
ReagentLIVE/DEAD™ Fixable Near-IR Dead Cell Stain Kit, for 633 or 635 nm excitationThermo FisherCatalog #L10119
Step 7
ReagentBD FACS Lysing Solution (10X)Becton Dickinson (BD)Catalog #349202
Step 11
ReagentBD Cytofix/CytopermBecton Dickinson (BD)Catalog #554722
Step 20
ReagentBD Perm/Wash bufferBecton Dickinson (BD)Catalog #554723
Step 20
Day 1. Whole blood stimulation for scrub typhus study
Day 1. Whole blood stimulation for scrub typhus study
Prepare pre-labelled 5 ml tubes to each contain 5 µl of “COCKTAIL” (co-stimulant) and NO Brefeldin A. Add the stimulants as follows to respective tubes as below
StimulantVolume of stimulant (µl)Concentration of Stimulant
HI-WCA-OT100prepared from 10E9 copies/ml of Live O. tsutsugamushi
SEB (positive control)100Dilute 1: 20 of stock SEB (1 mg/ml) in R10 Add 100 µl of this “SEB WBA” to each tube for final concentration of 10 µg/ml in 400 µl blood
R0 (negative control100

Co-stimulantManufacturerCatalog#final concentration
CD28BD Bioscience340975 1 µg/ml
CD49dBD Bioscience340976 1 µg/ml
COCKTAIL (co-stimulant)
Each provided as 200 µg in 0.01% azide in PBS; 1 mg/mL. Store at 4°C in the dark.
Dilute 1: 10 of each in a 1 ml tube, combine
3 µl anti-CD28
3 µl anti-CD49d
24 µl PBS. Label “COCKTAIL”
For 500 µL blood; add 5 µl of the above “COCKTAIL” solution for a final concentration of 1 µg/mL each.

Each subject in the study needs 3 x 5 ml tubes labelled with their ID number and stimulant (antigen or control) i.e. “HI-WCA-OT”(Antigen of interest, Heat inactivated whole cell antigen of Orientia tsutsugamushi ) “SEB” (Positive control) or “R0” (Negative control)
Add 400 µL of lithium heparinised blood to each tube, cap tightly, vortex.

Note
Use lithium heparinised blood collection tube only, Not other anticoagulants

Incubate at Temperature37 °C for 18-20 hours in CO2 incubator or in a water bath (optional).
Day 2. Harvest stimulated white blood cells and cryopreservation
Day 2. Harvest stimulated white blood cells and cryopreservation
Add 25 µL Brefeldin A (10 µg/mL)ReagenteBioscience™ Brefeldin A Solution (1000X)Becton Dickinson (BD)Catalog #00-4506-51

Incubate at Temperature37 °C for further 4 hours in CO2 incubator or in a water bath (optional).
Stain with Live-Dead Staining dye (Near IR) 1 µl which enables discrimination of live from dead cells in subsequent flow cytometry analysisReagentLIVE/DEAD™ Fixable Near-IR Dead Cell Stain Kit, for 633 or 635 nm excitationBecton Dickinson (BD)Catalog #L10119

Incubate on ice for 20 min.
Wash the sample once with Phosphate buffered saline (PBS) and centrifuge at 500 g for 5 min.

Note
Washing in PBS may help improve lysis

Remove supernatant by carefully pipetting without disturbing the pellet (RBC)
Red blood cell lysis (RBC) was performed by adding 3 ml of 1x FACS lysing solutionReagentBD FACS Lysing Solution (10X)Becton Dickinson (BD)Catalog #349202

Incubate at room temperature for 10 min. (to help RBC lysis), vortex for 30 s.
Spin in centrifuge for 5 min at 500 rcf
Remove supernatant by pouring off then vortex to resuspend pellet for 10 s
Adding 3 ml of 1x FACS lysing solution, vortex for 30 s.
Spin in centrifuge for 5 min at 500 rcf
Remove supernatant by pouring off then vortex to resuspend pellet for 10 s
Add 1 ml freezing mix to resuspended pellet and transfer 500 µl each into 2 labelled cryotubes (so that there is two tubes for each condition for freezing) followed by stepwise freezing to -80°C
Note
1) Freezing media: 10% DMSO combined with 90% Fetal bovine serum solution
2) In the case of field study scrub typhus samples, cells were stored at -80°C for a minimum of 2 weeks, then shipped on dry ice to the central laboratory and stored in Liquid Nitrogen until further analysis

Intracellular cytokine staining (ICS) for Flow cytometry
Intracellular cytokine staining (ICS) for Flow cytometry
To do ICS, cryopreserved stimulated whole blood samples were slowly thawed in a 37°C water bath
The cells are then undergo fixation and permeabilization using Cytofix (BD Biosciences, ReagentBD Cytofix/CytopermBecton Dickinson (BD)Catalog #554722 ) and Cytoperm/Wash (BD BiosciencesReagentBD Perm/Wash bufferBecton Dickinson (BD)Catalog #554723 ) according to the manufacturer’s instructions

Cells were stained with the following fluorochrome conjugated antibodies to assess polyfunctionality and memory:
Surface staining: CD8 V450 (clone RPA-T8, Cat 560347), CD3 V500 (clone SP34-2, Cat 560770), CD4 FITC (clone RPA-T4, Cat 555346 and clone M-T477, Cat 556615), CD45RA-PE (clone HI100, Cat 555489) all from BD Biosciences.
Intracellular staining: IFN-gamma APC (clone B27, BD Biosciences, Cat 554702), IL-2 PE (clone N7.48A, Beckman, Cat IM2718U) and TNF PCP-Cy5.5 (clone MAb11, eBioscience, Cat 45-7349-42).
After adding antibody for surface staining, the cells are incubated for 30 min at Temperature4 °C

Washing the cells in centrifuge for 5 min at 500 rcf
Remove supernatant by pouring off then vortex to resuspend pellet for 10 s
After adding antibody for intracellular staining, the cells are incubated for 30 min at Temperature4 °C
Washing the cells in centrifuge for 5 min at 500 rcf
Remove supernatant by pouring off then vortex to resuspend pellet for 10 s
Resuspend cells with 200 µl fixation buffer (BD Bioscience, Cat 554655) for subsequent flow cytometric analysis.
Acquisition of a minimum of 100,000 cells per sample was performed on a MACSQuant 10 analyzer (Miltenyi Biotec).