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Description
Human CD19 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: Adherent cells should be gently washed with pre-chilled PBS, then trypsinized and harvested by centrifugation at 1000×g for 5 minutes. Suspension cells can be harvested directly by centrifugation. Collected cells should be washed three times with pre-chilled PBS and resuspended 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. 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 19 (CD19) 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 Cluster of Differentiation 19 (CD19) 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 19 ELISA Kit | |||||||||||||||||||||||||||||||||
| Detection Type | Double antibody sandwich method | |||||||||||||||||||||||||||||||||
| Composition |
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| Background | The CD19 molecule (Cluster of Differentiation 19), also known as the B lymphocyte antigen CD19, B lymphocyte surface antigen B4, T cell surface antigen Leu-12, and CVID3, is a transmembrane protein encoded by the gene CD19. CD19 plays two major roles in B cells: on the one hand, it acts as an adaptor protein to recruit cytoplasmic signaling proteins to the membrane; on the other hand, it works in the CD19/CD21 complex to lower the threshold of the B cell receptor signaling pathway. Because it is present on all B cells, it is a biomarker for B lymphocyte development and lymphoma diagnosis, and can be used as a target for leukemia immunotherapy. | |||||||||||||||||||||||||||||||||
| 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, and other biological fluids |
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4.4 ★★★★★
Based on 1670 reviews
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Product Reviews
★★★★★ 5
Very cute, good quality
Style: Lambchop, Size: 10", Style: Lambchop, Size: 10"
Our Two year-old Great Pyrenees rescue loves her Lambchop. She’s fairly gentle with it, but it did accidentally rip so we had replace it since she loves it so much. No fault of the product. The product is very well made, She just got a little rough with it.
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Reviewed in the United States on April 27, 2026
★★★★★ 5
Excellent for chewers who like to extract squeekers. It has many.
Style: Lambchop, Size: 10"
This was my dog Clarks favorite toy. When he passed away last year, I saved his played with lamb chop and it sits near his ashes. My current dog Walter loves lamb chop too. I appreciate the squeekers in the all the mitts. It really adds so much to this toy. Great design. Durability will always be an issue with soft fluffy squeeky toys. I buy this knowing that half the fun for my dog is trying to extract all the squeekers.
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Reviewed in the United States on June 13, 2026
★★★★★ 5
Soft, strong, beautiful toy! My pup's favorite!!
Style: White, Size: 6"
My pups favorite toy is Lambchop!! They're soft, odor-free, and pretty chew-resistant, considering the work out, it goes through! I stay vigilant in keeping them in stock, for her playing pleasure. She enjoys doing her zoomies, squeaking as she goes. Stops, tossing it in the air, to catch it, them off zooming again! Thank You for the care taken in making this adorable toy, for hours of fun for my pup! Please keep them in stock. They're well worth every penny!!
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Reviewed in the United States on June 2, 2026
★★★★★ 5
BEST TOY!
Style: White, Size: 6"
I recently bought the Multipet INTERNATIONAL 843140 Lambchop Plush Squeak Toy Mini for my small dog, and it has quickly become her favorite toy. Here’s why this little squeak toy is a great addition to any pet’s collection:
Adorable Design
The Lambchop Plush Squeak Toy is absolutely adorable. It resembles the beloved character Lambchop, which adds a nostalgic charm for those who remember the classic TV show. The toy is well-crafted with a cute, friendly face and soft, plush material. Its small size makes it perfect for petite pets, and it’s just the right size for my dog to carry around and snuggle with.
Engaging and Fun
The built-in squeaker adds an extra layer of excitement for my pet. Every time she bites down, the squeak captures her attention and keeps her engaged for longer periods. It’s great for interactive play, fetch, and even as a comforting chew toy. My dog loves the noise it makes and often brings it to me to initiate playtime.
Durable Construction
Despite its soft and plush exterior, the Lambchop toy has proven to be quite durable. My dog is a moderate chewer, and after several weeks of play, the toy is still intact with no signs of wear and tear. The stitching is strong and has held up well against my dog’s playful bites and tugs. However, for very aggressive chewers, it might not last as long.
Easy to Clean
The toy is also relatively easy to clean. I’ve hand-washed it a few times to keep it fresh, and it dries quickly without losing its shape or squeak. The white color, while prone to getting dirty, can be easily spot-cleaned to maintain its appearance.
Perfect Size for Small Pets
At 6 inches, this toy is ideally sized for small dogs and even cats. It’s lightweight and easy for them to carry around. My dog can comfortably grip it in her mouth, and the toy is soft enough for her to cuddle with during nap time.
Value for Money
Considering its durability, engaging design, and the joy it brings to my pet, the Multipet Lambchop Plush Squeak Toy offers excellent value for money. It’s reasonably priced and provides hours of entertainment and comfort for my dog.
Overall Impression
Overall, the Multipet INTERNATIONAL 843140 Lambchop Plush Squeak Toy Mini is a fantastic toy for small pets. Its adorable design, engaging squeaker, and durable construction make it a worthwhile purchase. My dog loves it, and it has quickly become a staple in her toy collection. I highly recommend this toy to anyone looking for a cute and fun squeak toy for their small pet.
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Reviewed in the United States on June 18, 2024
★★★★★ 4
Not durable!
Style: White, Size: 24" Jumbo
Great toy, very soft, but my dog tore this up within an hour of getting it 💔 NOT FOR DOGS WHO CHEW EVERYTHING UP!! Not
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 2, 2026
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