1. REAGENT PREPARATION
1.1 Preparation of FACS buffer
- Make stock solution of 10% NaN3 in DPBS
- Transfer 497ml DPBS to a Schott bottle
- Add 1 ml 10% NaN3 solution to DPBS for an end concentration of 0.02% NaN3
- Add 2 ml 0.5 M EDTA to give an end concentration of 2 mM
- Add 5 g BSA and allow to dissolve
- Store solution at 4°C
2. PROTOCOLS FOR CELL-SURFACE STAINING OF MACROPHAGES, DC AND T CELLS
2.1 Standard extracellular staining protocol
- Harvest cells into cold DBPS. 2 × 105 cells are required for each staining reaction.
- Pellet cells by centrifugation at 300 g for 6 min
- Aspirate supernatant using vacuum pump
- Resuspend cells in 100 µl/reaction of FACS buffer + 10% FcR block
- Incubate at 4°C for 30 min
- Transfer blocked cell suspensions into FACS tubes at 100 µl/tube
- Add primary antibodies as indicated
- Incubate at 4°C in dark for 20 min
- Add 5 µl 7-AAD per reaction. Incubate at 4°C in dark for 10 min
- Add 2 ml DBPS per tube. Vortex
- Pellet cells by centrifugation at 300 g for 6 min
- Aspirate supernatant using vacuum pump.
- Resuspend cells in 200 µl DPBS for analysis by flow cytometry.
2.2 Amplification of PE or APC signals using FASER kit
- Harvest cells into cold DBPS. 2 × 105 cells are required for each staining reaction.
- Pellet cells by centrifugation at 300 g for 6 min
- Aspirate supernatant using vacuum pump
- Resuspend cells in 100 µl / reaction of FACS buffer + 10% FcR block
- Incubate at 4°C for 30 min
- Transfer blocked cell suspensions into FACS tubes at 100 µl / tube
- Add primary PE or APC conjugated antibody as indicated
- Incubate at 4°C in dark for 20 min
- Add 5 µl 7-AAD per reaction. Incubate at 4°C in dark for 10 min
- Add 2 ml DBPS per tube. Vortex
- Pellet cells by centrifugation at 300 g for 6 min
- Aspirate supernatant using vacuum pump.
- Resuspend cells in 80 µl FACS buffer + 20 µl FcR block + 10 µl FASER reagent 1
- Incubate at 4°C in dark for 10 min
- Wash one time in 2 ml DPBS by centrifugation at 300 g for 6 min
- Resuspend cells in 80 µl FACS buffer + 20 µl FcR block + 10 µl FASER reagent 2
- Incubate at 4°C in dark for 10 min
- Wash one time in 2 ml DPBS by centrifugation at 300 g for 6 min
- Resuspend cells in 80 µl FACS buffer + 20 µl FcR block + 10 µl FASER reagent 1
- Incubate at 4°C in dark for 10 min
- Wash one time in 2 ml DPBS by centrifugation at 300 g for 6 min
- Resuspend cells in 80 µl FACS buffer + 20 µl FcR block + 10 µl FASER reagent 2
- Incubate at 4°C in dark for 10 min
- Wash one time in 2 ml DPBS by centrifugation at 300 g for 6 min
- Resuspend cells in 200 µl DPBS for analysis by flow cytometry.
3. INTRACELLULAR STAINING OF HUMAN MREGS FOR IDO
- Harvest cells into cold DBPS. 5 × 105 Mregs are required for each staining reaction
- Pellet cells by centrifugation at 300 g for 6 min
- Aspirate supernatant using vacuum pump
- Resuspend cells in 3 ml DBPS
- Add 0.75 µl Fixable Live-Dead dye
- Incubate at 4°C in dark for 30 min
- Wash one time in 10 ml DPBS by centrifugation at 300 g for 6 min
- Resuspend cells in 300 µl FACS buffer + 10% FcR block for 15 min
- Transfer blocked cell suspensions into FACS tubes at 100 µl / tube
- Add primary PE-conjugated CD33 or isotype antibody as indicated in Figure 1 (3 reactions)
- Incubate at 4°C in dark for 30 min
- Wash samples one time in 2 ml DPBS by centrifugation at 300 g for 6 min
- Add 100 µl IC Fixation Buffer for 30 min RT in the dark
- Wash samples twice in 2 ml Perm Buffer by centrifugation at 300 g for 6 min
- Resuspend samples in 100 µl of FACS buffer + 10% FcR block for 15 min at 4°C
- Add intracellular staining antibodies as indicated for 30 min at RT in the dark
- Wash samples once in 2 ml Perm Buffer by centrifugation at 300 g for 6 min
- Resuspend cells in 200 µl DPBS for analysis by flow cytometry
See figure in Figures section.4. INTRACELLULAR STAINING OF HUMAN TREGS FOR FOXP3 AND HELIOS
4.1 Intracellular staining of cultured T cells
- Harvest cells into cold DBPS. 5 × 105 cells are required for each staining reaction
- Pellet cells by centrifugation at 300 g for 6 min
- Aspirate supernatant using vacuum pump
- Resuspend cells in 1 ml DBPS
- Add 1 µl Fixable Live-Dead dye
- Incubate at 4°C in dark for 30 min
- Wash one time in 10 ml DPBS by centrifugation at 300 g for 6 min
- Resuspend cells in 100 µl FACS buffer + 10% FcR block for 15 min
- Transfer blocked cell suspensions into FACS tubes at 100 µl / tube
- Add cell surface antibodies as indicated in Figure 2
- Incubate at 4°C in dark for 30 min
- Wash samples one time in 2 ml DPBS by centrifugation at 300 g for 6 min
- Aspirate supernatant using vacuum pump. Gentle vortex
- Add 500 µl Fixation/Permeabilization
- Incubate at 4°C in dark for 30 min
- Wash samples in 2 ml Perm Buffer by centrifugation at 300 g for 6 min
- Add intracellular staining antibodies (FoxP3-PE, optional Helios-APC) as indicated
- Incubate for 30 min at 4°C in the dark
- Wash samples 3 times in 2 ml Perm Buffer by centrifugation at 300 g for 6 min
- Resuspend cells in 200 µl Perm Buffer for analysis by flow cytometry
See figure in Figures section.4.2 Intracellular staining for FoxP3 in T cells from clinical blood samples
1 1 ml blood is used for each staining reaction. Dilute blood 1:1 with DBPS
2 Layer blood carefully onto 6 ml Biocoll in a 15 ml tube
3 Centrifuge at 2000 rpm, 20°C, for 25 min with no brake
4 Recover cell layer in the interface
5 Wash with 14 ml DPSB by centrifugation at 1600 rpm for 10 min
6 Aspirate supernatant using vacuum pump
7 Resuspend cells in 100 µl / reaction of FACS buffer + 10% FcR block
8 Incubate at 4°C for 30 min
9 Transfer blocked cell suspensions into FACS tubes at 100 µl / tube
10 Add cell surface antibodies as indicated in Figure 3
11 Incubate at 4°C in dark for 30 min
12 Add 2 ml DBPS per tube. Vortex
13 Pellet cells by centrifugation at 300 g for 6 min
14 Aspirate supernatant using vacuum pump. Gentle vortex
15 Add 500 µl Fixation/Permeabilization
16 Incubate at 4°C in dark for 30 min
17 Wash samples in 2 ml Perm Buffer by centrifugation at 300 g for 6 min
18 Add intracellular staining antibodies as indicated
19 Incubate for 30 min at RT in the dark
20 Wash samples 3 times in 2 ml Perm Buffer by centrifugation at 300 g for 6 min
21 Resuspend cells in 200 µl Perm Buffer for analysis by flow cytometry
See figure in Figures section.5. Gating strategy for identifying TIGIT+ Tregs among NSG mouse splenocytes
See figure in Figures section.