afcs_PP00000223.pdf

Assay of Cytokines in Tissue Culture Supernatants

AfCS Procedure Protocol PP00000223

Version 1, 03/17/04

The Bio-Plex cytokine assay employs a liquid suspension array for quantification

of cytokines in tissue culture supernatants or serum. Using this 96-well microtiter plate-

formatted assay, it is possible to profile the level of multiple cytokines in a single well.

The principle of the Bio-Plex cytokine assay is similar to a capture sandwich

immunoassay. An antibody directed against each desired cytokine is covalently coupled

to a different color-coded polystyrene bead. The conjugated beads are allowed to react

with a sample containing a known (standard) or unknown amount of cytokines. After

unbound cytokines are removed, biotinylated detection antibodies directed against a

different epitope on each cytokine are added to the reaction. The result is the formation

of a sandwich of antibodies around each cytokine. The complexes are detected by the

addition of streptavidin-phycoerythrin (streptavidin-PE), which has fluorescence

characteristics distinct from the beads. A specialized microtiter plate reader, which

allows for analysis of multiplexed bead-capture immunoassays in a single microtiter

well, carries out quantification. By reading beads individually in the mixture, the system

can detect each cytokine separately. The Bio-Plex software automatically calculates the

concentration of cytokines from standard curves derived from a mixture of cytokine

standards of a known amount.

Preparation for the Assay

1. Bring buffers and diluents in the reagent kit to room temperature prior to use. The

kit includes wash buffer A, assay buffer A, and detection antibody diluent A. The

following components should be kept on ice: streptavidin-PE, anti-mouse cytokine

18-plex conjugated beads, mouse cytokine 18-plex detection antibody, and

mouse cytokine standard. If frozen, thaw experimental samples and keep all on

ice as well.

2. Design experiment for a 96-well plate. Reserve 16 wells for the standard curve

(designated S1-S8, in table below) and 2 wells for the blank (culture medium).

Use the remaining wells for analyzing experimental samples (indicated by X

followed by a number, in table below).

10 11 12

S1 S5 Blank X7 X15 X23 X31 X39 X47 X55 X63 X71

S1 S5 Blank X8 X16 X24 X32 X40 X48 X56 X64 X72

S2 S6 X1 X9 X17 X25 X33 X41 X49 X57 X65 X73

S2 S6 X2 X10 X18 X26 X34 X42 X50 X58 X66 X74

S3 S7 X3 X11 X19 X27 X35 X43 X51 X59 X67 X75

S3 S7 X4 X12 X20 X28 X36 X44 X52 X60 X68 X76

S4 S8 X5 X13 X21 X29 X37 X45 X53 X61 X69 X77

S4 S8 X6 X14 X22 X30 X38 X46 X54 X62 X70 X78

3. Prepare 18-plex cytokine standard.

• Reconstitute lyophilized multiplex cytokine standards to a stock concentration

of 500,000 pg/ml by adding 50 µl of sterile distilled water. Vortex solution

gently for 5 sec and incubate on ice for 30 min. Note: Bio-Rad recommends

not using the standards >4 hr after reconstitution.

• Prepare serial dilutions of the 500,000 pg/ml standard stock solution.

Suggested concentrations, designated S1 to S8, are listed in the table below.

Dilutions should be made in culture medium such as RAW 264.7 growth

medium 1 (RAWGM1). Keep dilutions on ice.

Standard

sample

Concentration

(pg/ml)

1.95

7.8

31.25

125

500

2,000 8,000 32,000

4. Dilute samples in culture medium if necessary. Keep the diluted samples on ice.

5. Prepare the MultiScreen vacuum manifold following AfCS Procedure Protocol

PP00000221, Assembly and Use of MultiScreen Vacuum Manifold for Bio-Plex

Assay of Cytokines or Phosphoproteins .

6. Dilute the suspension of anti-mouse cytokine 18-plex conjugated beads.

• Vortex the anti-mouse cytokine 18-plex conjugated beads (25X) stock

solution at medium speed for 20 sec.

• Prepare a 25-fold working dilution of the suspension in Bio-Plex assay buffer

7. Cover all unneeded wells with the sealing tape provided with the kit. Employ razor

blade to cut the plastic sealer between those columns of the 96-well plate that will

be used and those that will not.

• Pour Bio-Plex assay buffer A into a pipettor solution basin (labeled “assay”).

• Pre-wet the filter plate with 100 µl per well of Bio-Plex assay buffer A using an

8-channel pipettor.

• Vacuumfilter.

• Blot the bottom of the filter plate on a stack of paper towels.

Cytokine Assay

8. Add bead suspension.

9. Vortex the working bead suspension at medium speed for 20 sec and pour into a

pipettor solution basin (labeled “beads”).

10. Add 50 µl of bead suspension to each well using an 8-channel pipettor.

11. Vacuum filter the plate and blot it.

12. Filter wash the beads twice with 100 µl Bio-Plex wash buffer A. Blot the bottom of

the filter plate after each filtration.

13. Vortex each standard dilution and immediately add 50 µl to the appropriate wells

(in duplicate). Add the appropriate blank, which is culture medium.

14. Vortex each sample for 20 sec and immediately add 50 µl to the appropriate

wells.

15. Cover the wells of the used columns in the 96-well plate with the rest of the

sealing tape used in step 7 . Blot the bottom of the plate.

Assay of Cytokines in Tissue Culture Supernatants

AfCS Procedure Protocol PP00000223

Page 2

16. Cover with aluminum foil to protect from light and incubate for 30 min at room

temperature with shaking (using a plate stirrer).

17. Shake the plate at 1,100 rpm for 30 sec, by slowly ramping up to this high speed.

18. Reduce speed to 300 rpm for the remainder of the incubation.

19. Turn on power to the Bio-Plex suspension array system and operate start-up

procedure (according to manufacturer’s instructions). Do not turn on more than 2

hr before use or it will go into sleeping mode, in which case, you will need to

operate start-up procedure again, which may take about 30 min.

20. Prepare mouse cytokine 18-plex detection antibody (during incubation and 10 min

prior to use).

21. Gently vortex the cytokine 18-plex detection antibody stock solution.

22. Note : the concentration of the detection antibody stock solution will vary as a

function of the degree of multiplexing of each panel.

• For single analytes, the detection antibody is provided in a 100X stock

solution.

• For 2 to 9 analytes, the detection antibodies are provided in a 50X stock

solution.

• For 10 or more analytes, the detection antibodies are provided in a 25X stock

solution.

23. Prepare the appropriate working dilution of the cytokine 18-plex detection

antibody stock solution in detection antibody diluent A.

24. Remove the sealing tape. Filter and blot the plate.

25. Wash 3 times with 100 µl Bio-Plex wash buffer A using an 8-channel pipettor.

26. Vortex the working dilution of the detection antibody gently, pour it into pipettor

solution basin (labeled “detection”), and add 25 µl to each well using an 8-channel

pipettor.

27. Cover the wells with sealing tape, and blot the bottom of the plate.

28. Cover plate with aluminum foil and incubate for 30 min at room temperature with

shaking.

29. Initiate shaking as described in steps 17 and 18 .

30. Calibrate the Bio-Plex suspension array system as described in the

manufacturer’s manual.

31. Prepare streptavidin-PE (during incubation of the beads, step 28, and 10 min prior

to use)

32. Vortex the streptavidin-PE (100X) stock solution vigorously.

33. Prepare a 100-fold working dilution of the streptavidin-PE (100X) stock solution in

Bio-Plex assay buffer A.

34. Remove the sealing tape. Filter and blot the plate.

35. Wash 3 times with 100 µl Bio-Plex wash buffer A using an 8-channel pipettor.

36. Vortex the streptavidin-PE working dilution, pour it into pipettor solution basin

(labeled “PE”), and add 50 µl to each well using an 8-channel pipettor.

37. Cover the wells with sealing tape, and blot the bottom of the plate.

38. Cover with foil and incubate for 10 min at room temperature with shaking.

39. Initiate shaking as described in steps 17 and 18.

40. Remove the sealing tape. Filter and blot the plate.

41. Wash 3 times with 100 µl wash buffer A using an 8-channel pipettor.

Assay of Cytokines in Tissue Culture Supernatants

AfCS Procedure Protocol PP00000223

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42. Resuspend the beads in each well with 125 µl of Bio-Plex assay buffer A using an

8-channel pipettor.

43. Cover the wells with sealing tape, and thoroughly blot the bottom of the plate.

44. Shake plate by slowly ramping up to 1100 rpm, maintain at that speed for 30 sec,

and slowly ramp down the speed to stop.

45. Remove the sealing tape and read the plate with Bio-Plex manager.

Reagents and Materials

Bio-Plex cytokine reagent kit: Bio-Rad; catalog no. 171-304000

Includes assay buffer A, wash buffer A, detection antibody diluent A, streptavidin-

PE, 96-well filter plate, 4 rolls sealing tape, and instructions

Bio-Plex mouse cytokine 18-plex panel: Bio-Rad; catalog no. 171-F11181

Includes anti-mouse cytokine 18-plex conjugated beads, mouse cytokine 18-plex

detection antibody, and mouse cytokine standard. 18-Plex cytokine standard

includes: IL-1α, IL-1β, IL-2, IL-3, IL-4, IL-5, IL-6, IL-12(p40), IL-12(p70), IL-17, G-

CSF, GM-CSF, INF-γ, KC, MIP-1α, RANTES, and TNF-α.

RAW 264.7 growth medium 1 (RAWGM1): AfCS Solution Protocol ID PS00000510

MultiScreen vacuum manifold (MultiScreen filtration system): Millipore; catalog no.

MAVM0960R

Includes manifold base, quick disconnect body, plastic ring (standard size),

manifold support grid, vacuum manifold gaskets, bleeder valve, plate alignment

tabs, vacuum pressure gauge, on/off valve, three-way connector, vacuum control

valve, hex key, straight connector, and FEP-lined PVC tubing ¼” I.D.

MultiScreen–BV plate (filter plates for high-throughput separations): Millipore; catalog

no. MABVN1210 10/PK

Includes non-sterile clear plates, lid, 1.2-µm hydrophilic, and low protein binding

Durapore membrane

Pipet-Lite multichannel pipette: Rainin; catalog no. L8-200

Pipettor solution basin: VWR; catalog no. 21007-970

IKA MTS2/4 digital stirrer (plate stirrer), 115V: VWR; catalog no. 82006-096

Bio-Plex suspension array system: Bio-Rad; catalog no. 171-000005

Includes array reader, microplate platform, computer, monitor, Bio-Plex manager

software, high-throughput fluidics (HTF) system, calibration kit, validation kit,

maintenance, calibration and validation (MCV) plate II, 20 L sheath fluid,

instructions

Assay of Cytokines in Tissue Culture Supernatants

AfCS Procedure Protocol PP00000223

Page 4

Author: Ruth Levitz

Date: 05/03/04

Approved: Susanne Mumby

Assay of Cytokines in Tissue Culture Supernatants

AfCS Procedure Protocol PP00000223

Page 5

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