Qdot™ Antibody (Ab) conjugates possess a bright fluorescence emission that makes them well suited for the detection of low-abundance extracellular proteins. Approximately the same size as R-phycoerythrin (R-PE) and compatible with existing organic fluorophore conjugates, Qdot™ Ab conjugates can be excited with any wavelength below their emission maximum, but are best excited by UV or violet light. The narrow, symmetric emission profiles of Qdot Ab conjugates allow for minimal compensation when using a single excitation source, and the very long stoke shifts enable better, more efficient multicolor assays using the 405 nm violet laser. Available in multiple colors for use in flow cytometry, these advantages make Qdot Ab conjugates powerful tools for antibody labeling and staining. Staining: Stain cells in any standard staining buffer, such as phosphate buffered saline (PBS) with 1% bovine serum albumin (BSA). We recommend analysis of cells within 18 hours of staining. If dilute reagent is used, dilute only the quantity of reagent to be used within one day. Qdot Ab conjugates may be mixed with other antibodies, but use the diluted conjugates on the day of dilution. Qdot Ab conjugates can be used for surface staining applications with most conventional sample preparation reagents, such as Cal-Lyse™ Lysing Solution and FIX and PERM™ reagents, with minimal effect on fluorescence. We have observed some batches of BD FACS™ Lysing Solution to interfere with Qdot Ab conjugate fluorescence. Each lot has been tested by flow cytometry using human peripheral blood leukocytes. This antibody recognizes the CD8 antigen, also known as T8 and Lyt2, and recognizes the alpha chain alone as well as the alpha-beta heterodimer. The isotype control for this antibody is mouse IgG2a, Cat. No. Q10015.
Instrument setup: Qdot Ab conjugates are excited optimally with UV or 405 nm light, although excitation can be obtained with any wavelength below the emission maximum of a given Qdot™ nanocrystal, such as with a 488-nm laser. Qdot Ab conjugates can be used on cytometers that do not have UV or violet excitation sources as long as they have appropriate emission filters. Make sure the cytometer has an appropriate emission filter for the Qdot Ab conjugate being used; alternate filters can be used as long as they capture the emission maximum, but filter width impacts spectral overlap corrections. And be sure to check for Qdot Ab conjugate emission in any channel that can capture nanocrystal emission off of other lasers on the cytometer. For Cat. No. Q10055: peak excitation 405 (488) nm/peak emission 655 nm; recommended filter 655/20 nm.
Store reagents at 2-8°C in the dark. Do not freeze. Because Qdot nanocrystals are conjugated to biological materials, some loss of activity may be observed with prolonged storage. When stored as instructed, expires six months from date of receipt unless otherwise indicated on product label. Qdot Ab conjugates are photostable, and do not need to be protected from light. However, if using Qdot Ab conjugates in combination with conventional fluorochrome conjugated antibodies, minimize light exposure during handling, incubation with cells, and prior to analysis. The Qdot Ab conjugates contain cadmium and selenium in an inorganic crystalline form. Dispose of the material in compliance with all applicable local, state, and federal regulations for disposal of these classes of material. For more information on the composition of these materials, consult the Safety Data Sheets (SDSs).
CD8 (Cluster of Differentiation 8) is a cell surface glycoprotein found on most cytotoxic T lymphocytes that mediate efficient cell-cell interactions within the immune system. The CD8 antigen acts as a co-receptor with the T-cell receptor on the T lymphocyte to recognize antigens displayed by an antigen presenting cell (APC) in the context of class I MHC molecules. CD8 is found on a T cell subset of normal cytotoxic/suppressor cells which make up approximately 20-35 % of human peripheral blood lymphocytes. The CD8 antigen is also detected on natural killer (NK) cells, subpopulations of peripheral blood null cells, thymocytes and bone marrow cells. The CD8 co-receptor functions as either a homodimer composed of two alpha chains, or as a disulfide-linked heterodimer composed of one alpha and one beta chain. Both alpha and beta chains share significant homology to immunoglobulin variable light chains. The majority of CD8+ T cells express CD8 as a alpha/beta heterodimer. In HIV, the HIV-2 envelope glycoprotein binds CD8 alpha chain (but not the beta chain).
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Protein Aliases: CD8; CD8 antigen, alpha polypeptide (p32); CD8 antigen, beta polypeptide 1 (p37); CD8a; CD8alpha; CD8b; CD8beta; Leu-2; Leu2 T-lymphocyte antigen; MAL; OKT8 T-cell antigen; T cell co-receptor; T lymphocyte surface glycoprotein beta chain; T-cell antigen Leu2; T-cell surface glycoprotein CD8 alpha chain; T-cell surface glycoprotein CD8 beta chain; T-lymphocyte differentiation antigen T8/Leu-2; T8 T-cell antigen
Gene Aliases: CD8; CD8A; CD8B; CD8B1; LEU2; LY3; LYT3; MAL; p32; P37