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Description
Human CD4 ELISA KitProduct Specification Usage Required experimental equipment: 1. Microplate reader (450nm) 2. High precision pipettes and pipette tips: 0. 5 10uL, 5 50uL, 20 200uL, 200 1000uL 3. 37C incubator 4. Distilled or deionized water Sample preparation and requirements: Tissue homogenization: Rinse the tissue with pre chilled PBS (0. 01M, pH 7. 4) to remove residual blood (lysed red blood cells in the homogenate will affect the measurement results). Weigh and
Product Specification
| Usage | Required experimental equipment: 1. Microplate reader (450nm) 2. High-precision pipettes and pipette tips: 0.5-10uL, 5-50uL, 20-200uL, 200-1000uL 3. 37°C incubator 4. Distilled or deionized water Sample preparation and requirements: Tissue homogenization: Rinse the tissue with pre-chilled PBS (0.01M, pH 7.4) to remove residual blood (lysed red blood cells in the homogenate will affect the measurement results). Weigh and mince the tissue. Add the minced tissue to the appropriate volume of PBS (generally a 1:9 weight-to-volume ratio, e.g., 1g of tissue sample to 9mL of PBS. The specific volume can be adjusted according to experimental needs and recorded. It is recommended to add protease inhibitors to the PBS) in a glass homogenizer and grind thoroughly on ice. To further lyse tissue cells, the homogenate can be sonicated or repeatedly frozen and thawed. Finally, centrifuge the homogenate at 5000×g for 5-10 minutes, and collect the supernatant for analysis. Cell Lysis Buffer: Gently wash adherent cells with pre-chilled PBS, then trypsinize and collect the cells by centrifugation at 1000×g for 5 minutes. Suspension cells can be collected directly by centrifugation. Wash the collected cells three times with pre-chilled PBS and resuspend in 150-200 μL of PBS per 1×10^6 cells (it is recommended to add protease inhibitors to the PBS; if the cell count is very low, reduce the PBS volume appropriately). Disrupt the cells by repeated freezing and thawing or sonication. Centrifuge the extract at 1500×g for 10 minutes at 2-8°C, and collect the supernatant for analysis. Cell Culture Supernatant: Centrifuge at 1000×g for 20 minutes. Collect the supernatant for analysis, or store at -20°C or -80°C, but avoid repeated freezing and thawing. Other biological fluids: Centrifuge at 1000xg for 20 minutes, remove the supernatant, and test. Pre-test preparation: 1. Remove the test kit from the refrigerator 10 minutes in advance and equilibrate to room temperature. 2. Prepare the standard gradient working solution: Add 1 mL of universal diluent to the lyophilized standard, let it stand for 15 minutes to completely dissolve, then gently mix (concentration is 20 ng/mL). Then dilute to the following concentrations: 20 ng/mL, 10 ng/mL, 5 ng/mL, 2.5 ng/mL, 1.25 ng/mL, 0.625 ng/mL, 0.3125 ng/mL, and 0 ng/mL. Serial dilution method: Take 7 EP tubes and add 500 μL of universal diluent to each tube. Pipette 500 μL of the 20 ng/mL standard working solution into the first EP tube and mix thoroughly to make a 10 ng/mL standard working solution. Repeat this procedure for subsequent tubes. The last tube serves directly as a blank well; there is no need to aspirate the liquid from the penultimate tube. See the figure below for details. 3. Preparation of Biotinylated Antibody Working Solution: 15 minutes before use, centrifuge the concentrated biotinylated antibody at 1000×g for 1 minute. Dilute the 100× concentrated biotinylated antibody to a 1× working concentration using universal diluent (e.g., 10µL concentrate + 990µL universal diluent). Prepare immediately before use. 4. Prepare the enzyme conjugate working solution: 15 minutes before use, centrifuge the 100× concentrated enzyme conjugate at 1000×g for 1 minute. Dilute the 100× concentrated HRP enzyme conjugate to a 1× working concentration with universal diluent (e.g., 10 μL of concentrate + 990 μL of universal diluent). Prepare immediately. 5. Prepare the 1× wash solution: Dispense 10 mL of 20× wash solution into 190 mL of distilled water (concentrated wash solution removed from the refrigerator may crystallize; this is normal. Allow to stand at room temperature until the crystals have completely dissolved before preparing). Procedure: 1. Remove the desired strips from the aluminum foil bag after equilibration at room temperature for 10 minutes. Seal the remaining strips in a ziplock bag and return to 4°C. 2. Sample addition: Add 100 μL of sample or standard of varying concentrations to the corresponding wells. Add 100 μL of universal diluent to the blank wells. Cover with a film and incubate at 37°C for 60 minutes. (Recommendation: Dilute the sample to be tested at least 1-fold with universal diluent before adding it to the ELISA plate. This will reduce the impact of matrix effects on the test results. The sample concentration should be multiplied by the corresponding dilution factor when calculating the final sample concentration. It is recommended to run replicates for all test samples and standards.) 3. Add Biotinylated Antibody: Remove the ELISA plate and discard the liquid without washing. Add 100 μL of Biotinylated Antibody Working Solution directly to each well. Cover with a film and incubate at 37°C for 60 minutes. 4. Wash: Discard the liquid and add 300 μL of 1x Wash Solution to each well. Let stand for 1 minute, shake off the wash solution, and pat dry on absorbent paper. Repeat this process three times (a plate washer can also be used). 5. Add Enzyme Conjugate Working Solution: Add 100 μL of Enzyme Conjugate Working Solution to each well. Cover with a film and incubate at 37°C for 30 minutes. 6. Washing: Discard the liquid and wash the plate five times as in step 4. 7. Adding substrate: Add 90 μL of substrate (TMB) to each well, cover with a sealing film, and incubate at 37°C in the dark for 15 minutes. 8. Adding stop solution: Remove the ELISA plate and add 50 μL of stop solution directly to each well. Immediately measure the OD value of each well at a wavelength of 450 nm. Calculating experimental results: 1. Calculate the average OD value of the standard and sample replicates and subtract the OD value of the blank well as a correction factor. Plot the standard curve of the four-parameter logistic function on double-logarithmic graph paper, with concentration as the horizontal axis and OD value as the vertical axis. 2. If the sample OD value is higher than the upper limit of the standard curve, dilute the sample appropriately and retest. Multiply the sample concentration by the corresponding dilution factor. |
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| Theory | This kit uses a double-antibody sandwich enzyme-linked immunosorbent assay (ELISA). Sample, standard, biotin-labeled detection antibody, and HRP conjugate are sequentially added to microwells pre-coated with a Cluster of Differentiation 4 (CD4) capture antibody. After incubation and washing, the sample is developed using the substrate TMB. TMB is converted to blue by HRP peroxidase and to yellow by acid. The intensity of the color is positively correlated with the presence of Cluster of Differentiation 4 (CD4) in the sample. The absorbance (OD) is measured at 450 nm using a microplate reader to calculate the sample concentration. | |||||||||||||||||||||||||||||||||
| Source | Human | |||||||||||||||||||||||||||||||||
| Synonym | Human Cluster Of Differentiation 4 ELISA Kit | |||||||||||||||||||||||||||||||||
| Detection Type | Double antibody sandwich method | |||||||||||||||||||||||||||||||||
| Composition |
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| Background | The CD4 molecule (CD4) is a glycoprotein that acts as a coreceptor for the T cell receptor (TCR). It is present on the surface of immune cells such as T helper cells, monocytes, macrophages, and dendritic cells. It was discovered in the late 1970s and initially referred to as Leu-3 and T4 (after the OKT4 monoclonal antibody that reacts with it) before being named CD4 in 1984. CD4 is a coreceptor for the T cell receptor (TCR), assisting the latter in communicating with antigen-presenting cells. The extracellular D1 domain of CD4 binds to the β2 region of MHC class II. It has also been shown to interact with SPG21 and Unc-119 (UNC-119). | |||||||||||||||||||||||||||||||||
| General Notes | 1. Strictly adhere to the specified incubation time and temperature to ensure accurate results. All reagents must be at room temperature (20-25°C) before use. Refrigerate reagents immediately after use. 2. Improper plate washing may result in inaccurate results. Ensure that all liquid in the wells is aspirated thoroughly before adding substrate. Do not allow the wells to dry out during incubation. 3. Remove any residual liquid and fingerprints from the bottom of the plate, as this will affect the OD value. 4. The substrate developer solution should be colorless or very light in color. Do not use substrate solution that has turned blue. 5. Avoid cross-contamination of reagents and specimens to prevent erroneous results. 6. Avoid direct exposure to strong light during storage and incubation. 7. Do not expose any reagents to bleaching solvents or the strong fumes emitted by bleaching solvents. Any bleaching agent will destroy the biological activity of the reagents in the kit. 8. Do not use expired products, and do not mix components with different product numbers and batches. 9. Recombinant proteins from sources other than the kit may not be compatible with the antibodies in this kit and will not be recognized. 10. If there is a possibility of disease transmission, all samples should be managed properly and samples and testing devices should be handled according to prescribed procedures. |
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| Storage Temp. | If the unopened kit is stored at 4°C, the shelf life is 6 months. | |||||||||||||||||||||||||||||||||
| Test Range | 0.31-20 ng/mL | |||||||||||||||||||||||||||||||||
| Applications | Tissue homogenates, cell lysates, cell culture supernatants, and other biological fluids |
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4.3 ★★★★★
Based on 700 reviews
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Product Reviews
★★★★★ 2
Nice but runs small
Size: 7 Big Kid, Color: Navy
The sandals are nice and not to hard or flimsy but they are cut very small.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 22, 2026
★★★★★ 4
Solid Kids Sandals, Overpriced Like Most Kids Shoes 🌞
Size: 11 Little Kid, Color: Brown, Size: 11 Little Kid, Color: Brown
My son hasn’t worn these yet since it’s December in Indiana and sandals + snow obviously don’t mix. 😂 So this review is based on first impressions rather than long term wear.
That said, these seem wider than a lot of typical kids’ sandals, which I REALLY appreciate since we tend to have wider feet in our family. #hobbitfeet
The quality feels pretty decent overall. They’re described as lightweight, and while they’re not insanely lightweight, they do have enough weight to feel semi-sturdy and not flimsy or cheap. I like the style and color, and I think they’ll work well for my son once warmer weather hits.
My main complaint is the price. At just under $24 at the time of this review, it feels a little high for kids’ sandals and for what these are. I really feel like $20 MAX would make more sense. Kids shoes are almost always priced like adult shoes, even though they clearly use less material, and that’s hard for me to understand and wrap my mind around. Overall, these seem solid for daily wear, I just wish the price was a bit more reasonable and affordable.
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Reviewed in the United States on December 31, 2025
★★★★★ 5
Great basic and timeless design
Size: 12 Little Kid, Color: Brown
These sandals are a great find! They’re super easy to get on and off thanks to the Velcro straps, which is a huge win for little ones learning to be more independent. The fit is adjustable and secure, so they stay in place well during all kinds of play.
The cork-style footbed is comfortable and gives good support, and the overall design feels sturdy enough to handle everyday wear. They’re lightweight but still durable, and have held up really well so far.
They also have a classic, versatile look that goes with just about everything, perfect for summer outfits. Overall, a reliable, comfortable sandal that’s great for active kids. Would definitely buy again!
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Reviewed in the United States on April 24, 2026
★★★★★ 5
Great option for boys or girls
Size: 13 Little Kid, Color: Black, Size: 13 Little Kid, Color: Black
This is really more of a unisex option for a sandal. I have sandals that look like this, and both of my children have worn this style. I ordered these for my daughter, with the plan to pass them down to my son if they're not too worn when she outgrows them. The style is very minimalistic, so it goes with lots of outfits. All the straps are easily adjustable, so you can get a good fit. I would say the length is true to size, but the width is maybe a bit wide. Nevertheless, the adjustable straps really help them fit well. They feel really sturdy and I appreciate that the sole has cushion to it. My daughter has worn these every day since I got them out of the closet and they're holding up well.
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Reviewed in the United States on February 19, 2026
★★★★★ 5
Fast shipping
Size: 5 Big Kid, Color: Black
Good sandals, the kid just didn't want them. Fast shipping and easy returns!
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Reviewed in the United States on June 11, 2026
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