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Description
Human sCD74 ELISA KitProduct Specification Usage Experimental equipment required for the experiment: 1. Microplate reader (450nm) 2. High precision pipette and gun tips: 0. 5 10uL, 5 50uL, 20 200uL, 200 1000uL 3. 37 constant temperature box 4. Distilled water or deionized water Sample processing and requirements: Serum: Place the whole blood sample collected in the serum separation tube at room temperature for 2 hours or at 4 overnight, then centrifuge at 1000g for 20
Product Specification
| Usage |
Experimental equipment required for the experiment: 1. Microplate reader (450nm) 2. High-precision pipette and gun tips: 0.5-10uL, 5-50uL, 20-200uL, 200-1000uL 3. 37℃ constant temperature box 4. Distilled water or deionized water Sample processing and requirements: Serum: Place the whole blood sample collected in the serum separation tube at room temperature for 2 hours or at 4℃ overnight, then centrifuge at 1000×g for 20 minutes, and take the supernatant, or store the supernatant at -20℃ or -80℃, but avoid repeated freezing and thawing. Plasma: Collect the specimen using EDTA or heparin as an anticoagulant. Centrifuge the specimen at 1000 × g for 15 minutes at 2-8°C within 30 minutes of collection. The supernatant can be assayed or stored at -20°C or -80°C, but avoid repeated freezing and thawing. 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 the tissue and mince it. Add the minced tissue to the appropriate volume of PBS (generally a 1:9 weight-to-volume ratio, e.g., 1 g of tissue sample to 9 mL 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 the supernatant can be assayed. 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 soluble CD74 (sCD74) capture antibody. After incubation and washing, the sample is developed using the substrate TMB. TMB converts to blue under the catalysis of HRP and to yellow under the action of acid. The intensity of the color is positively correlated with the amount of soluble CD74 (sCD74) in the sample. The absorbance (OD) is measured at 450 nm using a microplate reader to calculate the sample concentration. | |||||||||||||||||||||||||||||||||
| Source | Human | |||||||||||||||||||||||||||||||||
| Synonym | Human soluble CD74 ELISA Kit | |||||||||||||||||||||||||||||||||
| Detection Type | Double antibody sandwich method | |||||||||||||||||||||||||||||||||
| Composition |
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| Background | CD74 (cluster of differentiation 74), also known as the HLA-DR antigen-associated invariant chain or HLA class II histocompatibility antigen gamma chain, is a protein encoded by the CD74 gene. The invariant chain is a polypeptide that plays a key role in antigen presentation. It participates in the formation and trafficking of MHC class II peptide complexes to generate CD4+ T cell responses. The cell surface form of the invariant chain is known as CD74. CD74 is a cell surface receptor for the cytokine macrophage migration inhibitory factor (MIF). | |||||||||||||||||||||||||||||||||
| 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 | Serum, plasma, tissue homogenates and other biological fluids |
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4.4 ★★★★★
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Product Reviews
★★★★★ 5
Great Value
I've been really happy with this watch. I like a bigger, "chunkier" watch, and I specifically did NOT want smart watch features. This is a great weekend and chores watch. I can beat it up, do work in it, and not worry about it. And surprisingly, it's been pretty bullet proof so far. Since I've worn a watch for almost my whole life, I barely notice when I have one on. And I am not precious about them at all. This watch has hit countless door frames, washed hundreds of dishes in hot water, scrapes against the wall, tools, yard equipment. It's been absolutely rock-steady and I haven't needed to adjust the time at all, other than for daylight savings. At the price, it's unbeatable.
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Reviewed in the United States on May 31, 2024
★★★★★ 5
Fantastic for the money
I use this watch at work, so about 40 hours a week I wear it. I work outside in a commonly rainy area, and it's not uncommon for the watch to get wet. I've had it for a couple months or so now, and it really works great!
Honestly all of the complaints I have about it can be fixed solely by looking at the price.
The viewing angle isn't fantastic - it's a $13 watch.
It does lose a little bit of time (a second or two within a week, maybe) - it's a $13 watch.
The band is a bit uncomfortable (though it does hold very well, and has lots of size options) - it's a $13 watch.
Those are minor things. Here's the good stuff.
-Super easy to read
-Very easy to use and set
-Multiple features
-Is genuinely waterproof. I haven't held it underwater, or anything, but for what I would consider 'average' use, it is perfectly waterproof.
-Has an adjustable band that doesn't fall off
-Fairly tough. I don't treat mine very well and it's held up perfectly fine so far.
-It's cheap!
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Reviewed in the United States on February 21, 2019
★★★★★ 4
Cheap Gshock replacement, good value
For $13 this is a steal. It's essentially a casio illuminator w larger bright dial, press once for 5 sec of light then goes dark. Date, time (12 and 24hr), stop watch. The basics, all I needed. A+
Edit: updated the waterproofing is non-existent. It's not even water resistant so treat accordingly don't bring into the shower. The face plastic cracked on me from moderate use, still legible and since I don't test it with water not an issue. The buttons are very sensitive so activities like lifting can cause the bottom left button to depress and switch to stopwatch, or engage the stopwatch.
After over a year use I still rank this as a good value. It does the one thing I wish Casio would do is improve light illumination time. The buttons depress easier than Casio's which is a bonus imo, but can be aggravating to some. The water resistance doesn't exist so purchase accordingly.
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Reviewed in the United States on November 29, 2023
★★★★★ 5
Great watch, wristband wears out after a while. Uses a Skmei 1251 band.
Watch is reliable, doesn't drift in time too much, very efficient on battery, has gotten complimented on the look a few times and has a nice user interface. It's also great to be able to see the date without pressing any buttons.
The band has fatigued and snapped after many months of putting on and taking off the watch, but If you'd like to find a replacement band, search for Skmei 1251 wristbands.
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Reviewed in the United States on June 8, 2025
★★★★★ 5
Inexpensive sports watch that was easy to set up and works well.
I have had this watch for a few days. The included instructions were very basic, but I figured out how to set everything up pretty easily. The watch band is pretty adjustable, fits my fairly wide wrists very well. For the price, about half the cost of the name brand very similar watch it replaced, the watch works well, I am very pleased.
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Reviewed in the United States on February 22, 2026