The HTRF Human IL-21 detection kit is an immunoassay developed for the simple, rapid detection and quantification of soluble human IL-21 protein in cell supernatant, in a homogeneous (no wash steps, no separation steps) format.
| Feature | Specification |
|---|---|
| Application | タンパク質定量 |
| Dynamic Range | 82,9-2000 pg/mL |
| Limit of Detection | 8 pg/mL |
| Limit of Quantification | 37 pg/mL |
| Sample Volume | 14 µL |
The HTRF Human IL-21 detection kit is an immunoassay developed for the simple, rapid detection and quantification of soluble human IL-21 protein in cell supernatant, in a homogeneous (no wash steps, no separation steps) format.
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IL-21 (interleukin-21) is a type I cytokine belonging to the common gamma chain cytokine family. It is mainly produced by activated CD4⁺ T cells, particularly T follicular helper and Th17 subsets. IL-21 signals through a heterodimeric receptor and activates JAK1 and JAK3, leading to phosphorylation and activation of STAT3. IL-21 exerts a broad range of immune-modulatory effects on T cells, B cells, NK cells, dendritic cells, and macrophages, making it a central player in immune regulation, inflammation, and tumor immunity.
HTRF assays offer many advantages over other technologies:
The HTRF human IL-21 assay is based on a TR-FRET sandwich immunoassay involving two specific antibodies, one labelled with Eu3+-cryptate (donor) and the other with d2 (acceptor). Both antibodies bind to soluble human IL-21, and the donor-acceptor proximity leads to a fluorescent TR-FRET signal. The intensity of the signal is directly proportional to the concentration of soluble IL-21 present in the sample.
The HTRF human IL-21 assay can be run in a 96- or 384-well low volume white detection plate (20 µL final). As shown here, samples or standards are dispensed directly into the assay plate for the detection of IL-21 by HTRF reagents. The antibodies labelled with HTRF fluorophores may be pre-mixed and added in a single dispensing step. No washing steps are needed. The protocol can be further miniaturized or upscaled by simply resizing each addition volume proportionally.
| Sample size | 14 µL |
|---|---|
| Final assay volume | 20 µL |
| Kit component | Lyophilized standard, frozen detection antibodies & buffers |
| LOD & LOQ (in Diluent) | 8 & 37 pg/mL |
| LOD & LOQ (in RPMI) | 9 & 51 pg/mL |
| LOD & LOQ (in DMEM) | 13 & 43 pg/mL |
| Range | 82.9 - 2000 pg/mL |
| Time to result | 3h at RT |
| Species | Human |
Each of the 3 samples was measured 24 times, and the %CV was calculated for each sample. Samples were human recombinant IL-21.
| Sample | Mean [IL-21] pg/ml | CV |
|---|---|---|
| 1 | 180 | 10% |
| 2 | 463 | 13% |
| 3 | 1541 | 13% |
| Mean CV | 12% |
Each of the samples was measured in 3 independent experiments (3 separate days), and the %CV was calculated for each sample. Samples were human recombinant IL-21.
| Sample | Mean [IL-21] pg/ml | CV |
|---|---|---|
| 1 | 280 | 3% |
| 2 | 579 | 7% |
| 3 | 1648 | 1% |
| Mean CV | 4% |
The recovery percentages obtained from these experiments show the good dilution linearity of the assay. Human recombinant IL-21 was diluted in RPMI cell medium.
| Dilution factor | Expected [IL-21] pg/mL | Measured [IL-21] pg/mL | % dilution recovery |
|---|---|---|---|
| Neat | 1097 | 1097 | 100% |
| 2 | 548 | 608 | 111% |
| 4 | 274 | 300 | 109% |
| 8 | 137 | 160 | 117% |
| 16 | 69 | 78 | 113% |
A known amount of recombinant IL-21 was spiked into a dilution of supernatant from PBMC culture medium stimulated with PMA and ionomycin. The expected concentrations were compared to those measured in order to compute antigen recoveries (acceptance criteria: 80-120%). A 100% recovery indicates similar measurements of cytokine from a sample and the kit standard.
| Standard [IL-21] pg/mL | Native [IL-21] pg/mL | Expected [IL-21] pg/mL | Obtained [IL-21] pg/mL | Recovery % |
|---|---|---|---|---|
| 213 | 0 | 213 | 204 | 96% |
| 213 | 100 | 313 | 295 | 94% |
| 213 | 193 | 406 | 392 | 97% |
| 213 | 606 | 819 | 790 | 96% |
| 213 | 975 | 1188 | 1160 | 98% |
Cross reactivities were assessed using recombinant proteins tested at a concentration of 2000 pg/mL. Signals were interpolated on the assay standard curve to calculate concentrations. The assay is only compatible with human IL-21.
| Tested protein | Cross reactivity |
|---|---|
| Human IL-21 | 100% |
| Mouse IL-21 | 0% |
Human PBMCs (peripheral blood mononuclear cells) were seeded at 100,000 to 800,000 cells in a 96-well culture-treated plate in RPMI + 10% FBS medium, and stimulated with PMA (50ng/mL) and ionomycin (1µg/mL) for 48 hours at 37°C. Then 14 µL of supernatant were transferred into a white detection plate and 2 µL of activation reagent-2 and 4 µL of the pre-mixed HTRF IL-21 detection reagents were added. The HTRF signal was recorded after 3 hours of incubation at room temperature. The standard curve prepared in RPMI + 10% FBS allowed the interpolation of the human IL-21 concentration in each sample.
Human PBMC cells were seeded at 400,000 cells in a 96-well culture-treated plate in RPMI + 10% FBS culture medium and stimulated with increasing concentrations of PMA and Ionomycin for 48 hours at 37°C. Then 14 µL of supernatant were transferred into a white detection plate and 2 µL of activation reagent 2 and 4 µL of the pre-mixed HTRF IL-21 detection reagents were added. The HTRF signal was recorded after 3 hours of incubation at room temperature. The standard curve prepared in RPMI + 10% FBS allowed the interpolation of the human IL-21 concentration in each sample.
| Application |
Protein Quantification
|
|---|---|
| Automation Compatible |
Yes
|
| Brand |
HTRF
|
| Detection Modality |
HTRF
|
| Dynamic Range |
82,9-2000 pg/mL
|
| Limit of Detection |
8 pg/mL
|
| Limit of Quantification |
37 pg/mL
|
| Product Group |
Kit
|
| Sample Volume |
14 µL
|
| Shipping Conditions |
Shipped in Dry Ice
|
| Target |
IL-21
|
| Target Class |
Cytokine
|
| Target Species |
Human
|
| Technology |
TR-FRET
|
| Unit Size |
500 Assay Points
|
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