Human Total IL-18 Quantikine QuicKit ELISA

R&D Systems | Catalog # QK318

This product is in process of discontinuation.
R&D Systems
Discontinued Product
QK318 has been discontinued. An alternative/replacement product is available: DL180. View all IL-18/IL-1F4 products.

Key Product Details

Assay Length

80 minutes

Sample Type & Volume Required Per Well

Cell Culture Supernates (50 µL), Serum (25 µL), EDTA Plasma (25 µL), Heparin Plasma (25 µL)

Sensitivity

4.57 pg/mL

Assay Range

15.6-1000 pg/mL (Cell Culture Supernates, Serum, EDTA Plasma, Heparin Plasma)
View all IL-18/IL-1F4 ELISA Kits »

Product Summary for Human Total IL-18 Quantikine QuicKit ELISA

The Quantikine® QuicKit™ Human Total IL-18/IL-1F4 Immunoassay is a one step, 80-minute solid phase ELISA designed to measure human IL-18 in cell culture supernates, serum, and plasma. It contains E. coli-expressed recombinant human IL-18 and has been shown to accurately quantitate the recombinant factor free and in complex with IL-18 BPa. Results obtained using natural human IL-18 showed linear curves that were parallel to the standard curves obtained using the QuicKit™ standards. These results indicate that this kit can be used to determine relative mass values for natural human IL-18.

Product Specifications

Measurement

Quantitative ELISA

Detection Method

Colorimetric - 450nm (TMB)

Conjugate

HRP

Species

Human

Specificity

Natural and recombinant human IL-18.

Cross-reactivity

< 0.5% cross-reactivity observed with available related molecules. < 50% cross-species reactivity observed with species tested.

Interference

No significant interference observed with available related molecules.

Precision

Intra-Assay Precision (Precision within an assay) Two samples of known concentration were tested twenty times on one plate to assess intra-assay precision.

Inter-Assay Precision (Precision between assays) Two samples of known concentration were tested in ten separate assays to assess inter-assay precision. Assays were performed by at least three technicians.

Cell Culture Supernates

Intra-Assay Precision Inter-Assay Precision
Sample 1 2 1 2
n 20 20 10 10
Mean (pg/mL) 105 507 114 552
Standard Deviation 4.15 12.8 6.12 43.8
CV% 4.0 2.5 5.4 7.9

EDTA Plasma, Heparin Plasma, Serum

Intra-Assay Precision Inter-Assay Precision
Sample 1 2 1 2
n 20 20 10 10
Mean (pg/mL) 120 591 131 638
Standard Deviation 4.23 22.0 6.90 38.1
CV% 3.5 3.7 5.3 6.0

Recovery for Human Total IL-18 Quantikine QuicKit ELISA

The recovery of human IL-18 spiked to three different level throughout the range of the assay in various matrices was evaluated.

Sample Type Average % Recovery Range %
Cell Culture Supernates (n=4) 117 109-128
EDTA Plasma (n=2) 116 108-123
Heparin Plasma (n=2) 101 93-112
Serum (n=2) 101 85-117

Linearity

To assess the linearity of the assay, samples spiked with high concentrations of human IL-18 were serially diluted with the appropriate calibrator diluent to produce samples with values within the dynamic range of the assay.

Human IL-18/IL-1F4 ELISA Linearity

Scientific Data Images for Human Total IL-18 Quantikine QuicKit ELISA

Human IL-18/IL-1F4 ELISA Serum/Plasma Standard Curve

Human IL-18/IL-1F4 ELISA Serum/Plasma Standard Curve

Human IL-18 /IL-1F4 ELISA Cell Culture Supernate Standard Curve

Human IL-18 /IL-1F4 ELISA Cell Culture Supernate Standard Curve

Human Total IL-18 QuicKit Spiked Recovery Competitor Comparison

Total IL-18 is spiked at three known concentrations throughout the range of the assay and run to measure response of the spiked sample matrix. Serum recovery is 77% compared to 61% for the top competitor. EDTA plasma recovery is 89% compared to 60% for the top competitor. Heparin plasma recovery is 88% compared to 65% for the top competitor. In spike and recovery experiments, natural samples are spiked with the recombinant target analyte of interest to identify interference caused by sample matrices.

Human Total IL-18 QuicKit Spiked Linearity Competitor Comparison

Total IL-18 is spiked at high concentration in various matrices and diluted with appropriate Calibrator Diluent to produce samples with values within the dynamic range of the assay. The linearity is between 93%-104% compared to 58%-198% for the top competitor.

Preparation and Storage

Shipping

The product is shipped at ambient temperature. Upon receipt, store it immediately at the temperature recommended below.

Stability & Storage

Store the unopened product at 2 - 8 °C. Do not use past expiration date.

Background: IL-18/IL-1F4

Interleukin-18 (IL-18) is a proinflammatory cytokine in the IL-1 family that exerts distinct immune effects depending on the local cytokine environment. It is expressed as a 24 kDa precursor by endothelial and epithelial cells, keratinocytes, gamma delta T cells, and phagocytes. The precursor is activated intracellularly by Caspase-1 mediated proteolysis to release the 17 kDa mature cytokine. The precursor can also be released by necrotic cells for extracellular cleavage by multiple proteases. IL-18 activation is induced by infection or tissue damage and contributes to disease pathology in chronic inflammation (1-3). IL-18 binds to the widely expressed IL-18 R alpha which recruits IL-18 R beta to form the signaling receptor complex (4, 5). Its bioactivity is negatively regulated by interactions with IL-18 binding proteins and virally encoded IL-18BP homologs (6). In the presence of IL-12 or IL-15, IL-18 enhances anti-viral Th1 immune responses by inducing IFN-gamma production and the cytolytic activity of CD8+ T cells and NK cells (7, 8). In the absence of IL-12 or IL-15, however, IL-18 promotes production of the Th2 cytokines IL-4 and IL-13 by CD4+ T cells and basophils (9, 10). In the presence of IL-1 beta or IL-23, IL-18 induces the antigenindependent production of IL-17 by gamma delta T cells and CD4+ T cells (11). IL-18 also promotes myeloid dendritic cell maturation and triggers neutrophil respiratory burst (12, 13). In cancer, IL-18 exhibits diverse activities including enhancing anti-tumor immunity, inhibiting or promoting angiogenesis, and promoting tumor cell metastasis (14). Mature human IL-18 shares approximately 63% amino acid sequence identity with mouse and rat IL-18 (15). Alternative splicing in human ovarian cancer generates an isoform that is resistant to Caspase-1 activation (16). A cell surface form can be expressed on M-CSF induced macrophages and released in response to bacterial endotoxin (17).

Long Name

Interleukin 18

Alternate Names

IGIF, IL-1F4, IL-1g, IL18

Entrez Gene IDs

3606 (Human); 16173 (Mouse); 29197 (Rat); 397057 (Porcine); 574151 (Primate)

Gene Symbol

IL18

Additional IL-18/IL-1F4 Products

Product Documents for Human Total IL-18 Quantikine QuicKit ELISA

Certificate of Analysis

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Product Specific Notices for Human Total IL-18 Quantikine QuicKit ELISA

For research use only

Citations for Human Total IL-18 Quantikine QuicKit ELISA

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Protocols

View specific protocols for Human Total IL-18 Quantikine QuicKit ELISA (QK318):

These assays utilize an anti-tag coated microplate. Standards, samples, and controls are added to plate, followed by subsequent addition of an antibody cocktail. Following a 1 hour incubation, plates are washed and substrate is added and incubated for 20 minutes. Stop solution is then added and plates are read using a standard microplate reader.

QuicKit ELISA assay procedure

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