ELISA Kit for the Quantitative Analysis of Human CXCL4

The human CXCL4 ELISA (enzyme-linked immunosorbent assay) kit is used for detection of human CXCL4 in cell culture supernatants,human serum and plasma.THE ELISA KIT IS FOR RESEARCH USE ONLY. Please read this instruction manual carefully and check out the material provided before use, and you can contact with our company if any questions. You can enter our website or call us for other aim.

Introduction

CXCL4，also known as Platelet Factor 4 (PF4), is a small cytokine with a molecular weight of 8kDa.As a member of the CXC chemokine family, it shares features with CXCL8/IL8and CXCL7/NAP2.However, different from other CXC chemokines, CXCL4 does not contain an ELR motif and lacks binding to nearly all chemokine receptors. Recombinant human CXCL4 contains 70 amino acid residues, including the four highly conserved residues present in CXC chemokines.Mature human CXCL4 shares 60% amino acid sequence identity with mouse CXCL4.

The CXCR3 isoform CXCR3B,a potential high-affinity G-protein-coupled receptor for CXCL4, is expressed in human but not mouse.CXCL4 plays a significant role in coagulation.It is released from alpha-granules of activated platelets during platelet aggregation and could neutralize the anticoagulant effect of heparin. In addition, CXCL4 is observed to have multiple functions.CXCL4 is implicated in antiproliferation and anti-angiogenesis, interfering with FGF2 and VEGF heparin binding and thus inhibiting their signaling. CXCL4 can also be proinflammatory via participating in monocyte survival, macrophage differentiation, TNF-α induction and induction of endothelial cell apoptosis.

Principles of the Test

The kit is a solid sandwich enzyme-linked immunosorbent assay for detection of human CXCL4. An anti-human CXCL4 monoclonal antibody has been absorbed onto the wells of the microtiter strips provided. Samples including specimens or standards were pipetted into wells. The human CXCL4 in specimens or standards would be captured by the coated antibody and the free others were removed by washing. The human CXCL4 biotin-conjugated antibody were added and binds to human CXCL4 captured by the first antibody, which formed a sandwich. Streptavidin-HRP would be added and binds to the biotin conjugated antibody, then free Streptavidin-HRP would be removed during a wash step. After this, substrate solution would be added and catalyzed by the HRP, and a coloured product is formed. The intensity of the colored product is used to calculate in proportion to the amount of human CXCL4 in the original specimen.

Materials provided with the kit:

Reagent	96/48Test Kit
Human CXCL4 Antibody-Coated Wells	12strips/6strips
20×Standard Diluents	60 ml/30ml
Human CXCL4 Standard	2/1vial(s)
Human CXCL4 Detection Antibody	10ml/5ml
Streptavidin-HRP	10ml/5ml
Wash Buffer Concentrate 20×	30ml/15ml
TMB	10ml/5ml
Stop Solution	5ml/3ml
Plate Covers	3/2
Complete Instruction Manual	1

Specimen Collection

1. Collecting specimen as following:

A. The particulate of the cell culture supernatants should be removed before use.

B. Serum was obtained from clot at room temperature.

C. Please collect plasma with EDTA.

D. Assay immediately or store samples at -20℃. Avoid free-thaw cycles.

2. Antiseptic and anticoagulant should not appear in Serum samples.

3. Any particulate should be removed from samples before use.

4. Do not use grossly hemolyzed or lipemic samples.

Note: Strongly recommend that the serum and plasma samples should be diluents before use.

Precautions for use:

1. Please storage the Kit at 2～8℃。

2. Washing buffer concentrate may have crystal in low temperature, and you can melt its in water-bath before use.

3. Please discard the remains after use of the dissolved standard.

4. Avoid contact of substrate solution with oxidizing agents and metal.

5. Usage of disposable pipette tips avoid microbial contamination or cross-contamination of reagents or specimens.

6. Do not mix or substitute reagents with those from other lots or other sources.

7. To ensure the adequate mixture of added reagents, please tap gently the plate after the wells were filled with liquid.

8. Incubation temperature should be 25～28℃.

9. Wash step was crucial for whole assay process.

10. Duplicate wells of the same sample were recommended in assay process.

11. Avoid the foam while pour the liquid into wells.

12. For serum or plasma samples ,the biotin-conjugated antibody should be incubate for at least 90 minutes.

Reagent Preparation

1.The reagents should be warmed up to room temperature before use. The remanent reagents must reseal and put into refrigeratory again as soon as possible.

2.Dilute 1ml of wash buffer Concentrate into 19ml deionized or distilled water to work.

3. If you have a 5x standard diluent, please dilute it with double steaming water or deionized water.

4. Add the standard dilution solution to the bottle according to the volume of the label and wait 15 minutes for complete dissolution. Incubation temperature should be 25～28℃。.And in turn add the half concentration diluent by standard diluent .

Wash step:

Automated microplate washer or operating by pipette: Each well should be pour into 300 ul wash buffer and soak 15 or 30 seconds,then be aspirated, five times process were repeated. After the last wash, remove remaining wash buffer by aspirating. Invert the plate and blot it against clean paper towels.

Materials Required But Not Provided

1. pipettes and pipette tips

2. Microwell strip reader capable of reading at 450 nm (540 nm as optional reference wave length)

3. automated microplate washer

4.Glass-distilled or deionized water

Assay procedure

1.The needed strips were putted into the frame, the remains were returned into foil pouch and resealed.

2.Blank well were recommended, which only color reagent and stop solution be added. It is suggested that each testing with gradient density of standard for standard curve.

3.Add 100ul of standard or sample.Cover with the Plate Covers provided.Incubate for 2 hours at room temperature If is plasma serum samples, different sample dilution ratio is different, generally in the range of 3000 ~ 20000 times, If there is no definite scope, it is suggested that since 300 times, plus sample dilution shows as follows: Each hole add buffer 50 ul sample analysis, add in 1 x standard diluent dilution sample after five times, and sample amount to 50 ul.

4.Five times wash process were repeated.

5.Add 100ul of detection antibody. Cover with the Plate Covers provided.Incubate for 1 hour at room temperature.

6.Five times wash process were repeated.

7.Add 100ul of Streptavidin-HRP. Cover with the Plate Covers provided. Lucifugal incubation for 20 minutes at room temperature.

8.Five times wash process were repeated.

9.Add 100ul of TMB，Lucifugal incubation for 20 minutes at room temperature.

10.Add 50ul of stop solution to each well, determine the optical

density of each well within 10 minutes

Calculation of Results

1.Duplicates should be within 20 percent of the mean. Average absorbance values for each set of duplicate samples were used as detection results.

2.The blank absorbance values of subtract should be deducted.

3.Drawing a best fit curve through the points of graph. Draw the standard curve by plotting assayed OD value (on the Y axis) vs. concentration (on the X axis). The sample concentration was obtained based on its OD value founding in the standard concentration curve.

4.If the values obtained are not within the expected range of the standard, Samples should be dilute and assay again.

Typical Data and Standard Curve

 

Human CXCL4 Standard Curve

 

Sensitivity, Specificity, Repeatability

Sensitivity: repeated assays were evaluated and the minimum detectable dose was 14.5pg/ml.

Specificity : No Cross Reactivity with human GROa , GROb and mouse PF4 .

Repeatability: The coefficient of variation between wells or plates is less than 10 percent.