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Cluster of Differentiation (CD Antibodies)

Cluster of differentiation (CD) are cell surface molecules expressed on the cells of the immune system, which play key roles in immune cell-cell communication, sensing the microenvironment and in adaptive immunity. During lymphocyte maturation, immune cells will express complex variations of CD antigens on its cell surface, some of which are lost, while others are acquired at various stages either by interactions with antigen presenting cells (APC) or with other cells of the immune system. In flow cytometric immunophenotyping, monoclonal antibodies targeting CD antigens are extensively used for the identification and characterization of leukocyte populations, subpopulations and differentiation stages. AAT Bioquest features purified anti-human CD antibodies and fluorescently labeled CD antibody conjugates applicable for a wide range of research disciplines including, flow cytometry, immunohistochemistry and immunoblotting applications.

 

 

Immunophenotyping


Since immune cells express CD antigens at various stages of development or cell activation, they serve as reliable biomarkers for differentiating leukocyte populations and subpopulations, a technique referred to as immunophenotyping. For example, CD3 is a T cell co-receptor exclusively expressed on the surface of all mature T cells, while CD4 and CD8 antigens are expressed on the surface of T helper cells and cytotoxic T cells, respectively.

In addition, CD antigen expression can be influenced by certain disease conditions, and as such are often used as diagnostic or prognostic factors for the identification of leukemia's and lymphomas. For example, multiple myeloma is generally characterized by cells expressing CD38 but not CD19 and CD20. Because CD antigens are expressed at varying degrees and cell types, multiparameter flow cytometric analysis utilizing two or more combinations of fluorescently labeled CD antibodies enables clear resolution of particular cell type or subtype.
 

Table 1. Common CD markers used for the differentiation of leukocytes by flow cytometry.

Cell Type
Common Human CD Markers
Common Mouse CD Markers
T CellCD3, CD4, CD8CD3, CD4, CD8
B CellCD19, CD20CD45R/B220, CD19, CD 22 (B cell activation marker)
Dendritic CellCD11c, CD123CD11c, CD123
Natural Killer (NK) CellCD56CD335 (NKp46)
Stem Cell/PrecursorCD34 (hematopoietic stem cell only)CD34 (hematopoietic stem cell only)
Monocyte/MacrophageCD14, CD33CD11b/Mac-1, Ly-71 (F4/80)
GranulocyteCD66bCD66b, Gr-1/Ly6G, Ly6C
PlateletCD41, CD61, CD62CD41, CD61 (Integrin Β3), CD9, CD62P (activated platelets)
ErythrocyteCD235aCD235a, Ter-119
Endothelial CellCD146CD146 MECA-32, CD106, CD31, CD62E (activated endothelial cells)

 

CD Nomenclature


The CD nomenclature is a universally adopted designation system sanctioned by the World Health Organization (WHO). This system was designed for the classification of monoclonal antibodies (mAbs) directed against epitopes on the surface molecules of leukocytes. For difficult to characterize cell surface molecules, or ones only recognized by a single mAb, they are given the designation 'CDw' (e.g. CDw60 or CDw156). If the surface molecule is well characterized (recognized by two or more mAbs), then they are assigned an arbitrary value, such as CD4, CD8 or CD45.

CD nomenclature is also used to describe lymphocyte and leukocyte subtypes. The presence or absence of a specific antigen from the surface of the particular cell population is denoted with "+" or "-" respectively. A "+" symbol added to a CD number indicates the presence of that molecule on a cell or cell population, whereas a "-" indicates its absence. For example, a 'CD45+/CD20-' cell is one that expresses CD45, but not CD20. Cell populations can also be defined as hi or low indicating an overall variability in CD expression, particularly when compared to other cells being studied.
 

Table 2. CD nomenclature rules.

Designation
Placement
Definition
Example
Arbitrary numberFollows CD designationAssigned to a molecule recognized by two or more mAbs. The number designates both the group of mAbs recognizing the cell surface molecule as well as the molecule itself.CD4
Lowercase "w"Precedes arbitrary number designationAssigned to an insufficiently characterized molecule or ones only recognized by a single mAb. (W = Workshop)CDw15
Lowercase letterFollows arbitrary number designationAssigned to molecules that share a commonality such as a common chain or the same gene family.CD1a-CD1e share a common chain; CD66a-CD66f same gene family
Uppercase letterFollows arbitrary number designationIndicates a spliced variant of the extracellular domain of a cell surface molecule.CD45RA or CD45RO
Superscript "+/-"Follows arbitrary number designationIndicates the presence or absence of that molecule on a cell or cell population.CD4+CD8-
Superscript "high/low"Follows arbitrary number or uppercase letter designationIndicates either a low or high expression level of a CD molecule by a cell subset.CD4+CD45RAlowCD45ROhigh

 

CD Antibodies


AAT Bioquest offers a comprehensive selection of purified CD antibodies and fluorescently labeled CD antibody conjugates for multicolor flow cytometry, immunohistochemistry and functional assays. Available fluorophores include:
  • iFluor® dyes - bright, photostable dyes with optimized flow cytometry (FACS), fluorescence imaging and in vivo imaging applications.
  • mFluor™ dyes - bright, photostable dyes with optimized for flow cytometry (FACS) applications.
  • Alexa Fluor® dyes - suitable for flow cytometry (FACS) and fluorescence imaging applications.
  • Classic dyes - suitable for flow cytometry (FACS) and fluorescence imaging applications.
  • Phycobiliproteins and Tandem dyes - intensely bright dyes for flow cytometry (FACS) and multiparametric analysis.
 

Table 3. Available unconjugated purified CD monoclonal antibodies.

Antibody
Clone
Unit Size
Cat No.
Anti-human CD1 AntibodyHI149100 µg10010000
Anti-human CD2 AntibodyHIT11100 µg10020000
Anti-human CD2 AntibodyRPA-2.10100 µg10021000
Anti-human CD3 AntibodyHIT3a100 µg10030000
Anti-human CD3 AntibodyHIT3b100 µg10031000
Anti-human CD3 AntibodyOKT-3100 µg10034000
Anti-human CD3 AntibodySK7100 µg10033000
Anti-human CD3 AntibodyUCHT1100 µg10032000
Anti-human CD4 AntibodyRPA-T4100 µg10041000
Anti-human CD4 AntibodyHIT4a100 µg10040000


iFluor® Dyes Labeled to CD Antibodies


The following table outlines the fluorescence properties of available iFluor® dye labeled anti-human CD antibodies for use in flow cytometry (FACS) and fluorescence imaging applications. Conjugates made with iFluor® dyes exhibit superior brightness and photostability, outperforming Alexa Fluor® conjugates and other spectrally similar conjugates. For additional information on iFluor® dye-labeled CD antibodies and availability of other clones click on any label in the table below.
 

Table 4. Available iFluor® dye-labeled CD antibody conjugates.

Label
Ex (nm)
Em (nm)
ε¹
Φ²
CF 260 nm³
CF 280 nm⁴
iFluor® 35034444820,0000.950.830.23
iFluor® 40540242537,0000.910.480.77
iFluor® 43043349540,0000.780.680.3
iFluor® 45045150240,0000.820.450.27
iFluor® 48849151675,0000.90.210.11
iFluor® 51452755480,0000.830.250.11
iFluor® 53254356390,0000.680.260.16
iFluor® 546541557100,0000.670.250.15
iFluor® 555556569100,0000.640.230.14
iFluor® 560559571130,0000.570.0480.069
  1. ε = molar extinction coefficient at their maximum absorption wavelength (Units = cm-1M-1).
  2. Φ = fluorescence quantum yield in aqueous buffer (pH 7.2).
  3. CF at 260 nm is the correction factor used for eliminating the dye contribution to the absorbance at 260 nm (for oligo and nucleic acid labeling).
  4. CF at 280 nm is the correction factor used for eliminating the dye contribution to the absorbance at 280 nm (for peptides and protein labeling).

mFluor™ Dyes Labeled to CD Antibodies


The following table outlines the fluorescence properties of available mFluor™ dye labeled anti-human CD antibodies for use in flow cytometry (FACS). Each mFluor™ dyes is optimally excited by one of the major laser lines commonly equipped in flow cytometers, such as the 405 nm, 488 nm, 532 nm, 561 nm or 633 nm laser lines. For additional information on mFluor™ dye-labeled CD antibodies and availability of other clones click on any label in the table below.
 

Table 5. Available mFluor™ dye-labeled CD antibody conjugates.

Label
Ex (nm)
Em (nm)
ε¹
Φ²
CF 260 nm³
CF 280 nm⁴
mFluor™ UV37535438835,0000.940.0990.138
mFluor™ Violet 45040644525,0000.920.3380.078
mFluor™ UV46036245615,0000.860.350.134
mFluor™ Violet 50042649735,0000.810.7690.365
mFluor™ Violet 51040950430,0000.860.4640.366
mFluor™ Violet 54040053215,0000.641.3920.529
mFluor™ Blue 570552564120,0000.080.2280.179
mFluor™ Green 62052161750,0000.060.8950.569
mFluor™ Yellow 630546625110,0000.010.2830.413
mFluor™ Red 700657694250,0000.0290.1350.127
  1. ε = molar extinction coefficient at their maximum absorption wavelength (Units = cm-1M-1).
  2. Φ = fluorescence quantum yield in aqueous buffer (pH 7.2).
  3. CF at 260 nm is the correction factor used for eliminating the dye contribution to the absorbance at 260 nm (for oligo and nucleic acid labeling).
  4. CF at 280 nm is the correction factor used for eliminating the dye contribution to the absorbance at 280 nm (for peptides and protein labeling).

Alexa Fluor® Dyes Labeled to CD Antibodies


The following table outlines the fluorescence properties of available Alexa Fluor® dye labeled anti-human CD antibodies for use in flow cytometry (FACS) and fluorescence imaging applications. For additional information on Alexa Fluor® dye-labeled CD antibodies and availability of other clones click on any label in the table below.
 

Table 6. Available Alexa Fluor® dye-labeled CD antibody conjugates.

Label
Ex (nm)
Em (nm)
ε¹
Φ²
CF 280 nm³
Alexa Fluor® 35034344119,000N/D0.19
Alexa Fluor® 48849952073,0000.920.11
Alexa Fluor® 555553568155,0000.10.08
Alexa Fluor® 59459061892,0000.660.56
Alexa Fluor® 647650671270,0000.330.03
Alexa Fluor® 680681704183,0000.360.05
Alexa Fluor® 700696719205,0000.250.07
Alexa Fluor® 750752776290,0000.120.04
  1. ε = molar extinction coefficient at their maximum absorption wavelength (Units = cm-1M-1).
  2. Φ = fluorescence quantum yield in aqueous buffer (pH 7.2).
  3. CF at 280 nm is the correction factor used for eliminating the dye contribution to the absorbance at 280 nm (for peptides and protein labeling).

Classic Dyes Labeled to CD Antibodies


The following table outlines the fluorescence properties of available classic dye labeled anti-human CD antibodies for use in flow cytometry (FACS) and fluorescence imaging applications. For additional information on classic dye-labeled CD antibodies and availability of other clones click on any label in the table below.
 

Table 7. Available FITC, TRITC and other classic dye-labeled CD antibody conjugates.

Label
Ex (nm)
Em (nm)
ε¹
Φ²
CF 280 nm³
Pacific Blue™40445546,0000.780.2
FITC49151673,0000.790.254
Pacific Orange™40055125,000N/D0.6
TRITC54457085,0000.10.34
  1. ε = molar extinction coefficient at their maximum absorption wavelength (Units = cm-1M-1).
  2. Φ = fluorescence quantum yield in aqueous buffer (pH 7.2).
  3. CF at 280 nm is the correction factor used for eliminating the dye contribution to the absorbance at 280 nm (for peptides and protein labeling).

PE, APC, PerCP and Tandem Dyes Labeled to CD Antibodies


The following table outlines the fluorescence properties of available phycoerythrin (PE), allophycocyanin (APC), PerCP and tandem dye labeled anti-human CD antibodies for use in flow cytometry (FACS). Phycobiliproteins are uncharacteristically bright due to their high molar extinction coefficients and quantum yields, an enviable quality when imaging low-abundance targets. However, since phycobiliproteins photobleach rapidly, they are not recommended for microscopy. For additional information on phycobiliprotein-labeled CD antibodies and availability of other clones click on any label in the table below.
 

Table 8. Available PE, APC, PerCP and tandem dye-labeled CD antibody conjugates.

Label
Ex (nm)
Em (nm)
ε¹
Laser Line (nm)
PE5665741,960,000488 nm, 532 nm, 561-568 nm
PE-Texas Red®5676151,960,000488 nm, 532 nm, 561-568 nm
PE-Alexa Fluor® 6105676271,960,000488 nm, 532 nm, 561-568 nm
PE-Cy5®5656661,960,000488 nm, 532 nm, 561-568 nm
PE-iFluor® 6475696661,960,000488 nm, 532 nm, 561-568 nm
PE-Alexa Fluor® 7005667211,960,000488 nm, 532 nm, 561-568 nm
PE-Cy7®5667781,960,000488 nm, 532 nm, 561-568 nm
PE-iFluor® 7505667781,960,000488 nm, 532 nm, 561-568 nm
APC651660700,000633-647 nm
APC-iFluor® 700651710700,000633-647 nm
  1. ε = molar extinction coefficient at their maximum absorption wavelength (Units = cm-1M-1).

 

Additional Resources



Fluorescence Spectrum Viewer


Need assistance selecting the best fluorophore for your experiment, use our Fluorescence Spectrum Viewer:
  • View and compare fluorophores and fluorescent proteins for biological applications
  • Check spectral compatibility
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  • Save spectra configuration as a PNG or hyperlink