Cluster of Differentiation (CD)

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 TypeCommon Human CD MarkersCommon 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)
Epithelial CellCD326CD326 (EPCAM1)

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.

DesignationPlacementDefinitionExample
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 Antibody HI149 100 µg 10010000
Anti-human CD2 Antibody HIT11 100 µg 10020000
Anti-human CD2 Antibody RPA-2.10 100 µg 10021000
Anti-human CD3 Antibody HIT3a 100 µg 10030000
Anti-human CD3 Antibody HIT3b 100 µg 10031000
Anti-human CD3 Antibody OKT-3 100 µg 10034000
Anti-human CD3 Antibody SK7 100 µg 10033000
Anti-human CD3 Antibody UCHT1 100 µg 10032000
Anti-human CD4 Antibody RPA-T4 100 µg 10041000
Anti-human CD4 Antibody HIT4a 100 µg 10040000
Anti-human CD4 Antibody OKT-4 100 µg 10043000
Anti-human CD4 Antibody SK3 100 µg 10042000
Anti-human CD5 Antibody HISM2 100 µg 10050000
Anti-human CD5 Antibody L17F12 100 µg 10051000
Anti-human CD5 Antibody UCHT2 100 µg 10052000
Anti-human CD6 Antibody HI210 100 µg 10060000
Anti-human CD7 Antibody HIT7 100 µg 10070000
Anti-human CD8 Antibody SK1 100 µg 10081000
Anti-human CD8 Antibody HIT8a 100 µg 10080000
Anti-human CD8 Antibody OKT-8 100 µg 10082000
Anti-human CD9 Antibody HI9a 100 µg 10090000
Anti-human CD10 Antibody HI10a 100 µg 10100000
Anti-human CD11a Antibody HI111 100 µg 10110000
Anti-human CD11b Antibody HI11b 100 µg 10111000
Anti-human CD11b Antibody ICRF44 100 µg 10112000
Anti-human CD11c Antibody 3.9 100 µg 10113000
Anti-human CD13 Antibody WM15 100 µg 10130000
Anti-human CD14 Antibody 61D3 100 µg 10141000
Anti-human CD14 Antibody HI221 100 µg 10140000
Anti-human CD15 Antibody HI98 100 µg 10150000
Anti-human CD18 Antibody HI18a 100 µg 10180000
Anti-human CD19 Antibody HI19a 100 µg 10190000
Anti-human CD19 Antibody HIB19 100 µg 10192000
Anti-human CD19 Antibody SJ25C1 100 µg 10191000
Anti-human CD20 Antibody HI20a 100 µg 10201000
Anti-human CD20 Antibody HI47 100 µg 10200000
Anti-human CD21 Antibody HI21a 100 µg 10210000
Anti-human CD22 Antibody HIB22 100 µg 10220000
Anti-human CD24 Antibody HI45 100 µg 10240000
Anti-human CD25 Antibody HI25a 100 µg 10250000
Anti-human CD28 Antibody CD28.2 100 µg 10280000
Anti-human CD29 Antibody HI29a 100 µg 10290000
Anti-human CD33 Antibody HI33a 100 µg 10330000
Anti-human CD33 Antibody HIM3-4 100 µg 10331000
Anti-human CD34 Antibody 4H11 100 µg 10340000
Anti-human CD38 Antibody HI157 100 µg 10381000
Anti-human CD38 Antibody HIT2 100 µg 10380000
Anti-human CD40 Antibody HI40a 100 µg 10400000
Anti-human CD44 Antibody HERMES-1 100 µg 10443000
Anti-human CD44 Antibody HI44a 100 µg 10440000
Anti-human/mouse CD44 Antibody IM7 100 µg 10441000
Anti-human CD45 Antibody 2D1 100 µg 10454000
Anti-human CD45 Antibody HI100 100 µg 10455000
Anti-human CD45 Antibody HI151 100 µg 10452000
Anti-human CD45 Antibody HI185 100 µg 10453000
Anti-human CD45 Antibody HI30 100 µg 10450000
Anti-human CD45 Antibody HI73 100 µg 10451000
Anti-human CD45 Antibody UCHL1 100 µg 10456000

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™ 350 344 448 20,000 0.95 0.83 0.23
iFluor™ 405 402 425 37,000 0.91 0.48 0.77
iFluor™ 430 433 495 40,000 0.78 0.68 0.3
iFluor™ 450 451 502 40,000 0.82 0.45 0.27
iFluor™ 488 491 516 75,000 0.9 0.21 0.11
iFluor™ 514 527 554 80,000 0.83 0.25 0.11
iFluor™ 532 543 563 90,000 0.68 0.26 0.16
iFluor™ 546 541 557 100,000 0.67 0.25 0.15
iFluor™ 555 556 569 100,000 0.64 0.23 0.14
iFluor™ 560 559 571 130,000 0.57 0.048 0.069
iFluor™ 568 568 587 100,000 0.57 0.34 0.15
iFluor™ 594 587 603 180,000 0.53 0.05 0.04
iFluor™ 610 609 627 110,000 0.85 0.32 0.49
iFluor™ 633 638 652 250,000 0.29 0.062 0.044
iFluor™ 647 654 669 250,000 0.25 0.03 0.03
iFluor™ 660 660 677 250,000 0.26 0.07 0.08
iFluor™ 670 669 682 250,000 0.63 0.019 0.024
iFluor™ 680 683 700 220,000 0.23 0.097 0.094
iFluor™ 700 690 713 220,000 0.23 0.09 0.04
iFluor™ 710 712 736 190,000 0.14 0.12 0.07
iFluor™ 750 759 777 275,000 0.12 0.044 0.039
iFluor™ A7 759 780 275,000 0.1 0.03 0.03
iFluor™ 790 786 811 250,000 0.13 0.1 0.09
iFluor™ 800 801 820 250,000 0.11 0.03 0.08
iFluor™ 810 811 822 250,000 0.05 0.09 0.15
iFluor™ 820 820 849 250,000 N/A 0.11 0.16
iFluor™ 840 836 876 200,000 0.02 0.2 0.09
iFluor™ 860 852 877 250,000 N/A 0.1 0.14

Note

  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™ UV375 354 388 35,000 0.94 0.099 0.138
mFluor™ Violet 450 406 445 25,000 0.92 0.338 0.078
mFluor™ UV460 362 456 15,000 0.86 0.35 0.134
mFluor™ Violet 500 426 497 35,000 0.81 0.769 0.365
mFluor™ Violet 510 409 504 30,000 0.86 0.464 0.366
mFluor™ Violet 540 400 532 15,000 0.64 1.392 0.529
mFluor™ Blue 570 552 564 120,000 0.08 0.228 0.179
mFluor™ Green 620 521 617 50,000 0.06 0.895 0.569
mFluor™ Yellow 630 546 625 110,000 0.01 0.283 0.413
mFluor™ Red 700 657 694 250,000 0.029 0.135 0.127
mFluor™ Red 780 631 768 70,000 0.034 0.101 0.116

Note

  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® 350 343 441 19,000 N/D 0.19
Alexa Fluor® 488 499 520 73,000 0.92 0.11
Alexa Fluor® 555 553 568 155,000 0.1 0.08
Alexa Fluor® 594 590 618 92,000 0.66 0.56
Alexa Fluor® 647 650 671 270,000 0.33 0.03
Alexa Fluor® 680 681 704 183,000 0.36 0.05
Alexa Fluor® 700 696 719 205,000 0.25 0.07
Alexa Fluor® 750 752 776 290,000 0.12 0.04

Note

  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™ 404 455 46,000 0.78 0.2
FITC 491 516 73,000 0.79 0.254
Pacific Orange™ 400 551 25,000 N/D 0.6
TRITC 544 570 85,000 0.1 0.34

Note

  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)
PE 566 574 1,960,000 488 nm, 532 nm, 561-568 nm
PE-Texas Red® 567 615 1,960,000 488 nm, 532 nm, 561-568 nm
PE-Alexa Fluor® 610 567 627 1,960,000 488 nm, 532 nm, 561-568 nm
PE-Cy5® 565 666 1,960,000 488 nm, 532 nm, 561-568 nm
PE-iFluor™ 647 569 666 1,960,000 488 nm, 532 nm, 561-568 nm
PE-Alexa Fluor® 700 566 721 1,960,000 488 nm, 532 nm, 561-568 nm
PE-Cy7® 566 778 1,960,000 488 nm, 532 nm, 561-568 nm
PE-iFluor™ 750 566 778 1,960,000 488 nm, 532 nm, 561-568 nm
APC 651 660 700,000 633-647 nm
APC-iFluor™ 700 651 710 700,000 633-647 nm
APC-Cy7® 651 779 700,000 633-647 nm
APC-Alexa Fluor® 750 651 785 700,000 633-647 nm
APC-iFluor™ 750 651 791 700,000 633-647 nm
PerCP 477 678 350,000 488 nm
PerCP-Cy5.5 489 679 350,000 488 nm

Note

  1. ε = molar extinction coefficient at their maximum absorption wavelength (Units = cm-1M-1).

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