CD Markers
Search our extensive database of CD Markers.
CD 2 #
Alternative names: T11, Erythrocyte R, LFA-2
In humans and in mice, CD2 can be found on the surface of: T cells, NK cells, thymocytes, B cells, Monocytes
Ligands: CD58 (LFA-3), CD59, CD15, CD48
Associated molecules: CD16
Function: Adhesion between lymphocytes and other cells, lymphocyte activation, T cell development, component of immunological synapse.
Additional information: CD2 expression is upregulated upon thymocyte differentiation, playing an important role in T cell development, and is one of the earliest T cell markers. CD2 expression is also upregulated on the surface of activated T cells and memory T cells, and mediates intracellular activation signaling. Upon binding of CD2 on T cells to LFA3 on antigen-presenting cells (APCs), CD2 is enriched in the immunological synapse (IS) and is thought to play an important role for the formation, architecture and composition of the IS and recruitment of intracellular kinases. Similarly, CD2 plays a role in NK cell adhesion to target cells and affects the formation, architecture and composition of the IS with active recruitment of activating membrane molecules (e.g. CD16) and intracellular kinases, lowering the activation threshold.
Further reading:
CD2 Immunobiology. Binder C et al. Frontiers in Immunology (2020)
CD5 #
Alternative names: T1, Tp67, Leu-1, Ly-1, Lyt-1, Ly-12, Ly-A
In humans and in mice, CD5 can be found on the surface of: T cells and B cells
Ligands and associated molecules: CD72, BCR, gp35-37, ZAP-70, TCR, CD21
Function: negative regulation of T cell and B cell signaling, Regulation of T cell–B cell interactions
Additional information: CD5 expression is higher on T cells than B cells. Upon strong T cell activation, CD5 is upregulated. CD5 has been shown to negatively regulate T cell receptor signaling in the thymus. Though its role in the periphery is less understood. research implies function as a negative regulator of T cell signaling there as well. CD5 is also a negative regulator of B cell receptor (BCR) signaling, and stimulates IL-10 production by B cells.
Further reading:
CD7 #
Alternative names: gp40, TP41, LEU9
In humans and in mice, CD7 can be found on the surface of: T cells, thymocytes, NK cells, stem cells, B cells (in mice)
Ligands: K-12 (CD7 ligand)
Associated molecules: PI3K
Function: NK cell activation, T cell interactions
Additional information: CD7 is a member of the immunoglobulin superfamily. CD7 plays an activating role on NK cells by increasing proliferation and cytotoxicity, inducing upregulation of activation markers CD69 and CD25, and mediating cell interactions. CD7 molecules on the surface of T cells facilitate T cell interactions and provide costimulatory signals. CD7 also mediates T cell interactions during early lymphoid development.
Further reading:
CD9 #
Alternative names: p24, DRAp-1, MRP-1, Tspan29
CD9 can be found on the surface of:
- Human: T cells, B cells, macrophages/monocytes, granulocytes, platelets, endothelial cells, epithelial cells
- Murine: T cells, B cells, dendritic cells, precursor cells, macrophages/monocytes, granulocytes, platelets
Ligands and associated molecules: CD63, CD81, CD82, CD41/CD61, HLA-DR, Integrin β, CD315, CD316, PI4 kinase
Function: cell adhesion and migration, platelet activation and aggregation
Additional information: CD9 is a glycoprotein and member of the tetraspanin superfamily. CD9 molecules are involved in platelet activation and aggregation, as well as cell adhesion and motility. CD9 can modify signals that regulate the activation, proliferation, or differentiation of leukocytes by mediating cell–cell contact and associating with other cell surface molecules. Furthermore, CD9 has been shown to be involved in oncogenesis, cancer progression, and metastasis. CD9 is used as a marker for exosomes.
Further reading:
CD14 #
Alternative names: Lipopolysaccharide receptor (LPS-R), Mo2
CD14 can be found on the surface of:
- Human: granulocytes, macrophages/monocytes
- Murine: dendritic cells, granulocytes, macrophages/monocytes
Ligands: Lipopolysaccharide, endotoxin
Associated molecules: LBP, TLR4 (CD284), LY96, TLR2 (CD282)
Function: Lipopolysaccharide receptor, bacterial recognition
Additional information: CD14 is part of the CD1 family, which is structurally similar to major histocompatibility complexes (MHC). CD14 in complex with LBP binds Lipopolysaccharide (LPS), and mediates together with the Ly96 (MD-2):TLR4 complex the innate immune response against bacterial pathogens. CD14 also acts as a coreceptor for TLR2:TLR6 to mediate a response to diacylated lipopeptides and for TLR2:TLR1 to mediate a response to triacylated lipopeptides.
Further reading:
- Membrane Sorting of Toll-like Receptor (TLR)-2/6 and TLR2/1 Heterodimers at the Cell Surface Determines Heterotypic Associations with CD36 and Intracellular Targeting. Triantafilou M, et al. The Journal of Biological Chemistry (2006)
- Lipopolysaccharide-binding protein-mediated Toll-like receptor 4 dimerization enables rapid signal transduction against lipopolysaccharide stimulation on membrane-associated CD14-expressing cells. Tsukamoto H, et al. International Immunology (2010)
CD16 #
Alternative names: FCRIIIA, CD16a, Ly-17, FCGR3, FcgRIII, FcgRIIIa, IGFR3
In humans and mice, CD16 can be found on the surface of: T cells, dendritic cells, NK cells, macrophages/monocytes, granulocytes, B cells (in mice)
Ligands: IgG Fc
Functions: low-affinity Fc receptor, antibody binding, immune response modulation, phagocytosis, antibody-dependent cell-mediated cytotoxicity (ADCC)
Additional information: CD16 is a low-affinity IgG receptor and binds to the Fc region of IgG, with preferential binding to IgG1 and IgG3. CD16 is represented by two genes, CD16a and CD16b. CD16 triggers antibody-dependent cell-mediated cytotoxicity (ADCC), phagocytosis, degranulation, and proliferation. CD16b is only found on neutrophils and is used as a neutrophil marker. Monocytes and eosinophils express low levels of CD16, while mature neutrophils express high levels of CD16.
CD21 #
Alternative names: Complement receptor 2 (CR2), CR2/CR1, EBV-R, C3dR
CD21 can be found on the surface of:
- Human: T cells, B cells, dendritic cells, stem cells/precursors, epithelial cells
- Murine: T cells, B cells
Ligands: CD3d, Leu13, EBV
Associated molecules: CD23, CD19, CD81
Function: complement system, B cell activation and maturation
Additional information: CD21 is part of the complement system. CD21 is expressed on the surface of mature B cells, and together with CD19 and CD81, forms the B cell co-receptor complex, which can enhance the response to an antigen. CD21 is a marker for follicular dendritic cells and is critical for the activation of B cells in the germinal center and mature antibody responses. The interaction between CD21 and CD23 is necessary for the presentation of soluble protein antigens by B cells to CD4+ T cells.
CD25 (IL-2Rα) #
Alternative names: Tac antigen, p55, TCGFR, Ly-43
In humans and mice, CD25 can be found on the surface of: T cells, B cells, NK cells, macrophages/monocytes
Ligands: IL-2 (interleukin-2)
Associated molecules: CD122
Function: IL-2 receptor
Additional information: Along with other markers, CD25 is a surface marker used to identify regulatory T cells (Tregs). CD25 is the alpha chain of the IL-2 receptor and forms together with CD122 and CD132 to form high-affinity IL-2 receptors.
CD26 #
Alternative names: DPPIV, DPP4, ADABP, ADCP2
In humans and in mice, CD26 can be found on the surface of: T cells, B cells, NK cells, macrophages/monocytes, epithelial cells
Ligands: adenosine deaminase, collagen, CD45
Function: exopeptidase, T cell stimulation
Additional information: CD26 acts as a costimulatory molecule for T cells and B cells. CD26 has intrinsic enzymatic activity and cleaves polypeptides.
Further reading:
CD27 #
Alternative names: T14, S152, TP55, TNFRSF7
In humans and in mice, CD27 can be found on the surface of: T cells, B cells, NK cells
Ligands: CD70
Associated molecules: TRAF2, TRAF5, and SIVA1
Function: T cell and B cell costimulation, immune checkpoint, T cell immunity generation and maintenance of T cell immunity, NK cell effector modification, B cell activation
Additional information: CD27 is a member of the TNF-receptor superfamily. CD27 expression is upregulated upon T cell antigen binding and is considered an early surface marker for activation. As a costimulatory molecule, CD27 is important for effector T cell activation, survival, and proliferation; B cell activation; and induction of immunoglobulin synthesis. Interactions between CD27 and its ligand CD70 incite the NF-κB and c-Jun pathways, which are important in CD4+ and CD8+ T cell differentiation, T cell survival, preventing apoptosis, sustaining T cell effector functions, and forming memory T cells. After activation, CD27 is shed, though expression is maintained on memory T cells. Research shows that CD27 expression helps T cells with low-affinity TCR expression enter the cell cycle, which may explain its importance in memory T cell survival. NK cells expressing high levels of CD27 have a lower activation threshold and interact more closely with dendritic cells, while NK cells expressing lower levels of CD27 have higher activation thresholds and survive for longer periods.
Further reading:
- CD27 Dissects Mature NK Cells into Two Subsets with Distinct Responsiveness and Migratory Capacity. Hayakawa Y, Smyth MJ. The Journal of Immunology (2006)
- Targeting the T-cell co-stimulatory CD27/CD70 pathway in cancer immunotherapy: rationale and potential. Van de Ven K, Brost J. Future Medicine (2015)
CD31 #
Alternative names: PECAM-1, encoCAM, PECA1
In humans and in mice, CD31 can be found on the surface of: T cells, B cells, NK cells, macrophages/monocytes, granulocytes, platelets, endothelial cells
Ligands and associated molecules: CD38, glycosaminoglycans (GAGs), Integrin αvβ3, homophilic interaction with CD31, CD177
Function: cell adhesion, leukocyte migration, cell activation, angiogenesis
Additional information: CD31 is also known as platelet endothelial cell adhesion molecule (PECAM-1). Binding by CD31 on the surface of leukocytes and CD31 on the surface of endothelial cells facilitates endothelial migration. CD31 also has the ability to activate CD29 (Integrin β1) and CD18 (Integrin β2) to further augment cell adhesion and leukocyte migration. CD31 inhibits BCR and TCR signaling, preventing hyperreactivity and autoreactivity.
Further reading:
CD33 (Siglec-3) #
Alternative names: p67
In humans and in mice, CD33 can be found on the surface of: dendritic cells, stem cells/precursors, macrophages/monocytes, granulocytes
Ligands: sialylated glycoproteins or glycolipids
Associated molecules: SHP phosphatases
Function: sialic acid binding and immune system regulation, cell adhesion, cell–cell signaling, inhibitory receptor, apoptosis
Additional information: CD33 is an inhibitory receptor. Upon binding by sialic acid, activated CD33 is involved in inhibiting phagocytosis, cytokine production, and proliferation, and in induction of apoptosis. CD33 is the therapeutic target of gemtuzumab ozogamicin (Mylotarg), which is an antibody–drug conjugate used to treat acute myeloid leukemia.
CD38 #
Alternative names: T-10, ADP-ribosyl cyclase, Cyclic ADP-ribose hydrolase 1
In humans and in mice, CD38 can be found on the surface of: T cells, B cells, dendritic cells, NK cells, stem cell/precursor, macrophages/monocytes
Ligands: CD31, CD16
Associated molecules: Hyaluronic acid, CD3/TcR complex, HLA Class II
Function: signal transduction, cell adhesion, enzymatic activity and NAD+ regulation
Additional information: CD38 can be both a receptor and an enzyme. CD38 induces T cells to produce cytokines after binding CD31 on the surface of T cells. CD38 promotes NK cell adhesion to endothelial cells by binding CD31 on the surface of endothelial cells. Through the interaction with CD16 on endothelial cells, CD38 also mediates the movement of leukocytes out of the circulatory system and towards the site of tissue damage or infection. As an enzyme, CD38 catalyzes the formation of ADP-ribose and cyclic ADP-ribose from NAD+. CD38 is also highly and uniformly expressed on myeloma cells. Therapeutic antibodies targeting CD38, including isatuximab (Sarclisa) and daratumumab (Darzalex), are used in the clinic to treat multiple myeloma.
CD43 #
Alternative names: Leukosialin, Galactoglycoprotein, Sialophorin, SPN
In humans and in mice, CD43 is found on the surface of: T cells, NK cells, precursor cells, macrophages/monocytes, granulocytes, platelets
Ligands and associated molecules: CD62E, CD54, CD169, Hyaluronan, EZR, Moesin
Function: cell adhesion, T cell activation
Additional information: CD43 can be used as a marker for some lymphomas, such as T-cell lymphomas, Burkitt lymphoma, mantle cell lymphoma, and small lymphocyte B-cell lymphoma. CD43 can regulate T cell adhesion and activation. CD43 mediates Th17 recruitment and rolling on vascular endothelium.
Further reading:
- CD43 Functions as an E-Selectin Ligand for Th17 Cells In Vitro and Is Required for Rolling on the Vascular Endothelium and Th17 Cell Recruitment during Inflammation In Vivo. Velazquez F, et al. The Journal of Immunology (2016)
- Structural requirements for CD43 Function. Walker J, Green JM. The Journal of Immunology (1999)
CD45 #
Alternative names: Protein tyrosine phosphatase, receptor type C (PTPRC), Leukocyte Common Antigen (LCA), T200, B220, Ly5
In humans and in mice, CD45 can be found on the surface of: T cells, B cells, NK cells, macrophages/monocytes, dendritic cells, granulocytes, precursor cells
Ligands: Galectin-1
Associated molecules: p56lck, p59fyn, Src kinases
Function: regulation of TCR and BCR signaling, regulation of cell growth and differentiation
Additional information: CD45 is a tyrosine phosphatase and a pan-hematopoietic cell marker. In humans and mice, CD45 exists in different isoforms: CD45RA, CD45RB, CD45RC, and CD45RO (with CD45RA and CD45RC not being expressed on granulocytes). CD45RA and CD45RO are used in immunohistochemistry to distinguish the T cell activation status. In mouse models, allelic variants of CD45, CD45.1 and CD45.2, are used as markers to track hematopoietic cells following congenic bone marrow transplants. CD45 activates T cells upon strongly binding to a ligand, but suppresses T cell activity when the signal is too weak. CD45 is needed to activate the kinase Lck, which is necessary for TCR and BCR signaling.
Further reading:
CD45 functions as a signaling gatekeeper in T cells. Courtney AH, et al. Science Signaling (2019)
CD48 #
Alternative names: Blast-1, BCM-1, Hulym3, OX-45, MEM-102
In humans and in mice, CD48 can be found on the surface of: T cells, B cells, NK cells, dendritic cells, macrophages/monocytes, stem cells/precursors
Ligands: CD2, CD244 (2B4)
Function: cell adhesion, lymphocyte activation
Additional information: CD48 is a member of the CD2 sub-family of the immunoglobulin superfamily. On T cells, the interaction between CD48 and CD2 promotes lipid raft formation and contributes to the formation of the immunological synapse. Interactions between CD48 and its high-affinity receptor, CD244, regulate NK cell and T cell cytotoxicity.
Further reading:
Roles of CD48 in regulating immunity and tolerance. McArdel SL, et al. Clinical Immunology (2006)
