Biolegend, 285064, Spark Red™ 718 anti-human CD21 (Flexi-Fluor™) Antibody, 50μg

CD21 is a 145 kD transmembrane protein also known as complement C3d receptor (C3dR), complement receptor 2 (CR2), and Epstein-Barr virus receptor. CD21 is expressed on B cells, follicular dendritic cells, subsets of normal thymocytes and T cells, and some epithelial cells. CD21 is the receptor used by Epstein-Barr virus to infect B cells and is also the complement receptor for C3d. CD21 has also been shown to interact with a number of proteins, including CD23, CD19, annexin VI, CD81, iC3b, complement receptor 1 (CR1, CD35), and interferon-alpha 1 (IFN-α1).
50μg
Verified Reactivity: Human
Reported Reactivity: African Green, Baboon, Cynomolgus
Antibody Type: Monoclonal
Host Species: Mouse
Formulation: Phosphate-buffered solution, pH 7.2, containing 0.09% sodium azide
Preparation: The antibody was purified by affinity chromatography and conjugated with Spark Red™ 718 under optimal conditions.
Concentration: 0.2 mg/mL
Storage & Handling: The antibody solution should be stored undiluted between 2°C and 8°C, and protected from prolonged exposure to light. Do not freeze.
Application: FC
Recommended Usage: Flexi-Fluors™ are provided at a standard 0.2 mg/mL concentration. We recommend titrating this reagent to determine the optimal concentration for each application. For many flow cytometry applications, conjugated antibodies perform well at concentrations ranging from 0.03 to 1.0 µg per million cells in 100 µL. We recommend testing a range of concentrations starting from 10 µg/mL.For example, make five 1:1 serial dilutions of the 0.2 mg/mL antibody. Add 5 µL of each dilution (including the undiluted antibody) to 100 µL of cells (at 107 cells/mL) to test six concentrations -- 1.0, 0.5, 0.25, 0.125, 0.06, and 0.03 µg per million cells in 100 µL volume. Compare staining patterns or create a titration curve using the MFI or staining index to determine the optimal concentration. * Spark Red™ 718 has a maximum excitation of 697 nm and a maximum emission of 711 nm.
Excitation Laser: Red Laser (633 nm)
Application Notes: Additional reported applications (for the relevant formats) include: immunohistochemical staining of acetone-fixed frozen sections4.
Additional Product Notes: For more information about Flexi-Fluors™, visit our Flexi-Fluor™ page and review FAQs associated with this product line.
Application References(PubMed link indicates BioLegend citation): Björck P, et al. 1993. Eur. J. Immunol. 23:1771. Frémeaux-Bacchi V, et al. 1996. Eur. J. Immunol. 26:1497. Ling NR, et al. 1995. Clin. Exp. Immunol. 101:369. Wang, C, et al. 2011. BMC Immunol. 12:53. (IHC)
RRID: AB_3106324 (BioLegend Cat. No. 285064)
Structure: Transmembrane protein, multiple SUSHI domains, approximate molecular weight 145 kD
Distribution: Expressed on B cells, follicular dendritic cells, subsets of normal thymocytes and T cells, some epithelial cells
Function: Epstein-Barr virus receptor on B cells used for infection
Interaction: CD23, CD19, complement component 3, annexin VI, CD81, iC3b, complement receptor 1, interferon alpha 1
Ligand/Receptor: C3d, EBV
Cell Type: B cells, Dendritic cells, Epithelial cells, T cells, Thymocytes
Biology Area: Cell Biology, Complement, Costimulatory Molecules, Immunology, Innate Immunity, Neuroinflammation, Neuroscience
Molecular Family: CD Molecules
Antigen References: 1. Kishimoto T, Eds. 1997. Leukocyte Typing VI. Garland Publishing Inc. 2. Moore MD, et al. 1987. Proc. Natl. Acad. Sci. USA 84:9194. 3. Szakonyi G, et al. 2001. Science 292:1725. 4. Weis JJ, et al. 1984. Proc. Natl. Acad. Sci. USA 81:881.
Gene ID: 1380
UniProt: View information about CD21 on UniProt.org
Clone: Bu32
Regulatory Status: RUO
Workshop: V CD21.4, VI CD21.5
Other Names: Complement C3d receptor (C3dR), complement receptor 2 (CR2), Epstein-Barr virus receptor
Isotype: Mouse IgG1, κ
Q: What are Flexi-Fluors?
A: Flexi-Fluors are rapidly made-to-order conjugated antibodies. The technology, manufacturing processes, and specifications used to create Flexi-Fluors are the same as our regular catalog products. However, the optimal concentration and performance of each Flexi-Fluor must be determined by the customer.
Q: How quickly will I receive my order?
A: We aim to ship Flexi-Fluors within 2-3 weeks of receipt of your order. However, depending on your location, shipping times may vary.
Q: How are Flexi-Fluors different from regular catalog products?
A: Flexi-Fluors are made on demand, specifically for you. Flexi-Fluors are manufactured using the same high-quality standards, and specifications as other catalog products. For faster delivery, Flexi-Fluors are not tested by flow cytometry to determine optimal concentrations or evaluate performance. This testing needs to be performed by the customer.
Q: How do I determine the optimal concentration for using my Flexi-Fluor? How should I titrate my antibody?
A: Flexi-Fluors are provided at a standard 0.2 mg/mL concentration. We recommend that you titrate your antibody to determine the optimal concentration to use for your application. For many flow cytometry applications, conjugated antibodies perform well at concentrations ranging from 0.03 to 1.0 µg per million cells in 100 µL volume. We recommend that you test a range of concentrations starting from 10 µg/mL. 

For example, make five 1:1 serial dilutions of your 0.2 mg/mL antibody.  Add 5 µL of each dilution (including the undiluted antibody) to 100 µL of cells (at 107 cells/ml) to test six concentrations - 1.0, 0.5, 0.25, 0.125, 0.06, and 0.03 µg per million cells in 100 µL volume. Compare staining patterns or create a titration curve using the MFI or staining index to determine the optimal concentration.
Q: I can’t find the antibody-dye combination that I need. When will it be available?
A: We continuously update our catalog, introducing scores of new products every month. Please get in touch with our Technical Service team for an update on new products or recommendations for suitable alternatives to complete your panel. Or contact Custom Solutions to inquire about our affordable custom conjugation services.
Q: I need help to validate the performance of my Flexi-Fluor. Who should I contact?
A: Please get in touch with Technical Service for assistance.
Q: Can I order more than 50 μg of a Flexi-Fluor?
A: Yes, you can order multiple vials of the same Flexi-Fluor products.  We cannot guarantee, however, that these vials will be bottled from the same lot. For bulk single-lot orders, contact our Custom Solutions team.
Q: What is the expiration date of my Flexi-Fluor?
A: Expiration dates can be found on the vial label or by using our CoA lookup tool.
Q: What if my requested antibody-dye combination doesn't perform as expected?
A: Flexi-Fluor™ products have been carefully selected by our scientists for their excellent conjugation properties and broad compatibility. In the rare case that an antibody-dye combination does not perform as expected due to the unique characteristics of a specific pairing, please contact our Technical Service team. We will work with you to identify alternative options to meet your panel requirements.