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CD4 Products

CD4 Antibody [Unconjugated]
CD4 Antibody [Unconjugated]
Species: Hu
Applications: WB, Simple Western, IHC, ICC/IF
Host: Goat Polyclonal
Conjugate Catalog # Availability Size Price
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Antibody Pairs
CD4 Antibody Pair [HRP]
CD4 Antibody Pair [HRP]
Species: Ma
Applications: ELISA
Host: Mouse Monoclonal
Conjugate Catalog # Availability Size Price
Mouse CD4 ELISA Kit (Colorime ...
Mouse CD4 ELISA Kit (Colorimetric)
Species: Mu
Applications: ELISA
Rat CD4 ELISA Kit (Colorimetr ...
Rat CD4 ELISA Kit (Colorimetric)
Species: Rt
Applications: ELISA
Rabbit CD4 ELISA Kit (Colorim ...
Rabbit CD4 ELISA Kit (Colorimetric)
Species: Rb
Applications: ELISA
CD4 Overexpression Lysate
CD4 Overexpression Lysate
Species: Hu
Applications: WB
Recombinant Human sCD4 Protei ...
Recombinant Human sCD4 Protein
Species: Hu
Applications: Bioactivity
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Recombinant Cynomolgus Monkey ...
Recombinant Cynomolgus Monkey CD4 ...
Species: Pm-Cm
Applications: Bioactivity
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Recombinant Human CD4 Protein ...
Recombinant Human CD4 Protein, CF
Species: Hu
Applications: Bioactivity
Formulation Catalog # Availability Price  


CD4 (cluster of differentiation 4), also known as L3T4 or T4, is a 55 kDa single chain type I transmembrane glycoprotein belonging to the immunoglobin (Ig) superfamily. CD4 is predominantly expressed on most thymocytes, a subset of mature T lymphocytes, and weakly on monocytes, tissue macrophages, dendritic cells, and granulocytes. It is also expressed on neurons and glial cells in the brain (1). CD4 is expressed along with CD8 on double positive T cells during their development in the thymus. Either CD4 or CD8 expression is then lost giving rise to single positive (SP) CD4+ or CD8+ mature T cells. CD4+ SP cells (T helper cells) further differentiate into multiple subsets of CD4+ cells including Th1, Th2, Th17, Tfh, and Treg cells which regulate humoral and cellular immunity (2). The extracellular region of CD4 consists of 372 amino acids (aa) with four immunoglobin-like domains (D1-D4). The structures of D1 and D3 resemble variable (IgV) domains while D2 and D4 resemble constant (IgC) domains (3).

Given its critical role in T cell development, CD4 also has diverse immunology-related functions. CD4 acts as a coreceptor with the T-cell receptor (TCR) during T cell activation and thymic differentiation by binding directly to major histocompatibility complex (MHC) class II antigens and associating with the protein tyrosine kinase, Lck (4). This interaction contributes to the formation of the immunological synapse (5). Defects in antigen presentation cause dysfunction of CD4+ T cells and the almost complete loss of MHC II expression on B cells in peripheral blood, as observed in severe combined immunodeficiency (SCID) (6). CD4 also functions as a receptor for the human immunodeficiency virus (HIV) by binding to gp120, the envelope glycoprotein of HIV-1. It has been shown that the V-like domains are critical for binding to gp120 (7). In immune mediated and infectious diseases of the central nervous system, CD4 functions as an indirect mediator of neuronal damage (8).


1. Omri, B., Crisanti, P., Alliot, F., Marty, M., Rutin, J., Levallois, C., . . . Pessac, B. (1994). CD4 expression in neurons of the central nervous system. International Immunology, 6(3), 377-385. doi:10.1093/intimm/6.3.377

2. Wan, Y. Y., & Flavell, R. A. (2009). How diverse-CD4 effector T cells and their functions. Journal of Molecular Cell Biology, 1(1), 20-36. doi:10.1093/jmcb/mjp001

3. Wu, H., Myszka, D. G., Tendian, S. W., Brouillette, C. G., Sweet, R. W., Chaiken, I. M., & Hendrickson, W. A. (1996). Kinetic and structural analysis of mutant CD4 receptors that are defective in HIV gp120 binding. Proceedings of the National Academy of Sciences, 93(26), 15030-15035. doi:10.1073/pnas.93.26.15030

4. Doyle, C., & Strominger, J. L. (1987). Interaction between CD4 and class II MHC molecules mediates cell adhesion. Nature, 330, 256-259. doi:10.1038/330256a0

5. Vignali, D. A. (2010). CD4 on the road to coreceptor status. The Journal of Immunology, 184(11), 5933-5934. doi:10.4049/jimmunol.1090037

6. Tasher, D., & Dalal, I. (2012). The genetic basis of severe combined immunodeficiency and its variants. The Application of Clinical Genetics, 5, 67-80. doi:10.2147/tacg.s18693

7. Arthos, J., Deen, K. C., Chaikin, M. A., Fornwald, J. A., Sathe, G., Sattentau, Q. J., . . . Sweet, R. W. (1989). Identification of the residues in human CD4 critical for the binding of HIV. Cell, 57(3), 469-481. doi:10.1016/0092-8674(89)90922-7

8. Buttini, M., Westland, C. E., Masliah, E., Yafeh, A. M., Wyss-Coray, T., Mucke, L. (1998). Novel role of human cd4 molecule identified in neurodegeneration. Nature Medicine, 4(4), 441-446. doi:10.1038/nm0498-441


Entrez Mouse
Uniprot Human
Product By Gene ID 920
Alternate Names
  • CD_antigen: CD4
  • CD4 antigen (p55)
  • CD4 antigen
  • CD4 molecule
  • CD4 receptor
  • CD4
  • CD4mut
  • T-cell surface antigen T4/Leu-3
  • T-cell surface glycoprotein CD4

Research Areas for CD4

Find related products by research area and learn more about each of the different research areas below.

Adaptive Immunity
CD Markers
Cell Biology
Cellular Markers
Cytokine Research
Stem Cell Markers

Related CD4 Blog Posts

Check out the latest blog posts on CD4.
Cluster of Differentiation 3 (CD3) (OKT3 clone) as a Marker of Immune Response Efficiency
Our immune system is a powerful defense mechanism against infection, however different variables can cause our immune response to work for or against us.  CD3 (cluster of differentiation 3) is one component of our immune signal response that is co...    Read more.
MHC Class I and the Herpes Simplex Virus
MHC molecules (also known as major histocompatibility complex molecules) assist in the presentation of antigens to T cells in order to eradicate foreign pathogens.  These molecules are highly polymorphic, meaning that they exist in multiple varian...    Read more.
Transferrin and the blood brain barrier
Transferrin, an iron binding protein that facilitates iron uptake in cells, is an integral part of a mechanism that may introduce antibody therapies to the central nervous system. Currently, the brain’s ability to take in antibody therapies i...    Read more.
Topics in CD11b: The innate immune response
Integrins are transmembrane receptors composed of alpha and beta chains, where beta-integrins are mainly expressed in leukocytes. Leukocytes are white blood cells that act in the immune system to defend our body against foreign pathogens.  Integrin...    Read more.
The role of MHC Class II RT1B and immune response post brain injury
The major histocompatibility complex (MHC) is responsible for binding peptide fragments arising from pathogens in order to display them on the cell surface for recognition from immune cells.  Once recognized, the foreign pathogen is typically evade...    Read more.
The CD4 Antibody: More than Just a Cellular Marker
CD4 is a member of the cluster of differentiation family of proteins, mainly expressed on the surface of thymocytes and a specific subset of mature T-cells. CD4 antibody studies have also shown it expressed on monocytes, cortical cells, microglial cel...    Read more.
Potential breakthrough in HIV research means therapeutic HIV antibodies may be coming soon.
Research antibodies have long been used to advance HIV/Aids research, however researchers at the California Institute of Technology have recently published a study [PMID: 22033520] developing a new antibody that may someday be used clinically to neutr...    Read more.
A Multicolored Approach to CD4 Antibody Assays
Novus Biologicals offers the widest selection of conjugated CD4 antibody products, with a database that's continually expanding to take into account the latest developments. This includes CD4 antibodies conjugated to Dynomics and PE fluorescent dyes, ...    Read more.
FOXP3: Master Regulatory Transcriptional Factor
FOXP3, a forkhead family transcription factor specially expressed in regulatory T (Treg) cells, controls the expression of many key immune-regulatory genes. Treg cells are a population of T lymphocytes that have critical roles in the immune system hom...    Read more.
CD4, HIV and T Cell Signaling
CD4, also known as Cluster of Differentiation 4, interacts with major histocompatibility complex class II antigens, acts as a receptor for the human immunodeficiency virus and induces the aggregation of lipid rafts. It is expressed in T lymphocytes, B...    Read more.
CD4 - An Important Co-receptor Assisting TCRs
The cluster of differentiation 4 (CD4) protein is a surface, type I membrane-embedded glycoprotein that is found on a wide range of cells: T-lymphocytes, B-cells, macrophages, granulocytes, and developmentally-dependent regions specific to the brain. ...    Read more.
Flow Cytometry Basics for the Non-Expert
By Jody Bonnevier, PhD.Flow cytometry: A Challenging Interdisciplinary ApplicationFlow cytometry has long been the cell analysis method of choice for immunologists, however more and more disciplines have recognize...    Read more.
mTOR Signaling and the Tumor Microenvironment
By Yoskaly Lazo-Fernandez, PhD The mammalian target of rapamycin (mTOR) is a conserved serine/threonine kinase that, as a member of two distinct intracellular protein complexes, mTORC1 and mTORC2, regulates protein ...    Read more.
CD20 (Cluster of differentiation 20, Membrane-spanning 4-domains subfamily A member 1 (MS4A1), CVID5, B-lymphocyte surface antigen B1)
CD20 is a human B-lymphocyte surface molecule that spans the membrane four times and is expressed on both normal and malignant cells. The CD20 antigen displays a unique expression pattern among hematopoietic cells - it is present on human pre B-ly...    Read more.
Success of combined IL-10 and IL-12 therapy in colon cancer depends on IFN-gamma and gut barrier integrity
By Jamshed Arslan, Pharm. D., PhD. Colon cancer is responsible for over 600,000 deaths per year worldwide. Colon cancer can be classified into two categories: mismatch repair (MMR)-deficient and MMR-proficient cancers...    Read more.
Lymphocyte activation gene 3 (LAG3): No lag time in immune response
The LAG3 protein belongs to the Ig superfamily and contains 4 extracellular Ig-like domains (D1-D4). This molecule plays an key role in the immune response through negative regulation of T-cell proliferation, function, and homeostasis. It is required ...    Read more.
CD8 alpha - Marker for Cytotoxic T Lymphocytes
What is CD8?The T-cell co-receptor CD8 is a cell-surface glycoprotein that bridges the lipid bilayer by interacting externally with ligands, such as major histocompatibility complex (MHC) class I, as well as internally with signaling molecules such...    Read more.

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Early T cell response is associated with mild COVID-19 and rapid SARS-CoV-2 clearance
Jamshed Arslan, Pharm D, PhD SARS-CoV-2 induces both humoral and cellular immunity. A vaccine or natural infection invokes SARS-CoV-2-specific humoral components (antibodies from activated B cells) and cellular resp...    Read more.
Immune Cell Metabolic Flux Influences Type I Diabetes
By Hunter MartinezWhat is Immunometabolism?It is well established that abnormal metabolic environments can be a risk factor for disease development. One characteristic example is the role of dyslipidemia (high lev...    Read more.
Synthetic Biotic Medicine as Immunotherapy Against Cancer: Evidence From Arginine-Producing Engineered Bacteria
By Jamshed Arslan, Pharm D, PhDWhat do nuts, dairy and red meat have in common? In addition to the fact that they are all edible, one of the answers is L-arginine. This amino acid improves T cell’s respons...    Read more.
Is Monkeypox Still A Threat?
By Jamshed Arslan, Pharm D, PhD Monkeypox is not deadly like its cousin, smallpox, nor is it as contagious as COVID-19. Yet, it continues to scare the world. In May 2022, a multinational outbreak of a cont...    Read more.
Read more CD4 related blogs.