All cells express characteristic markers (proteins, lipids, glycosylation, etc.) that can be used to help distinguish unique cell types. Cell markers can be expressed both extracellularly on the cell's surface or as an intracellular molecule. This page covers surface and intracellular cell markers for a variety of cell types including immune cells, stem cells, and central nervous system cells. Select your cell of interest from the dropdown menus below to learn about the markers they express.


Myeloid Cells


Neural Cells

Stem Cells

Additional Cells



Astrocytes are a subtype of glial cells found in the nervous system. They are characterized by having a many-branched star shape in the brain. Astrocytes perform a variety of functions including providing nutrients and support for neurons and synaptic transmission, maintenance of extracellular ion balance, support of endothelial cells and maintenance of the blood-brain barrier, and repairing and scarring in the brain and spinal cord after traumatic injuries.

Intracellular Markers

Extracellular Markers


Basophils are a rare subset of granulocytes that contain large granules containing histamine, proteoglycans, proteolytic enzymes, lipid mediators (leukotrienes) and cytokines. These granules release their contects with activation by IgE or other stimuli. Basophils are involved in defense against parasites and play a role in allergic reactions.
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B Cell

B cells are lymphocytes that are responsible for the humoral immune response, in contrast to the cell-mediated immune response governed by T cells. B cells make antibodies against antigens, perform the role of antigen-presenting cells (APCs) and eventually develop into memory B cells after activation by antigen interaction. B cells are an essential component of the adaptive immune system.
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Embryonic Stem Cell

Embryonic stem cells are pluripotent stem cells capable of developing into any one the 220 different cell types found in the human body. They are derived from the inner mass of embryos at the blastocyst stage, 4-5 days post-fertilization.

Endothelial Cell

Endothelial cells are cells that line the interior surface of blood vessels. They are involved in many aspects of vascular biology, including atherosclerosis, providing barrier function, blood clotting, inflammation, angiogenesis, and control of blood pressure.


Eosinophils are a small subset of granulocytes that play a role in the innate immune defense against parasites and viruses, while also contributing to allergy and asthma. Similar to other granulocytes they release a complex mixture of inflammatory mediators upon degranulation, such as: reactive oxygen species, lipid mediators, cytokines, and growth factors.
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Epithelial Cell

Epithelial cells are cells that line the inner and outer surfaces of the body, constituting the outer most surface of the epithelium. Epithelial tissues can develop from ectoderm, mesoderm, or endoderm. The main functions of epithelia are protection (skin), absorption (lining of the intestines), and secretion (lining of the stomach wall).

Extracellular Markers


Erythrocytes, commonly known as red blood cells, are the most common cell type in the blood. They are required for the delivery of oxygen to body tissues through the use of hemoglobin, which imparts the cell's red color. In humans, mature erythrocytes lack a nucleus and most organelles, and as a result, are bioconcave shaped and quite flexible, allowing them to flow easily through the circulation.
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Extracellular Markers


Fibroblasts are cells of mesenchymal origin that produce extracellular matrix and collagen, which are materials that provide 3-dimensional structure for animal tissues and organs. Fibroblast are important for wound healing and are the most common cell type found in the connective tissues in animals. In stem cell research, mouse embryonic fibroblast are commonly used as "feeder" cells to help maintain human embryonic stem cells.

Extracellular Markers

Hematopoietic Stem Cell

Hematopoietic stem cells (HSCs) are bone marrow-derived multipotent stem cells that give rise to all the blood cell types from the myeloid (monocytes and macrophages, neutrophils, basophils, eosinophils, erythrocytes, megakaryocytes/platelets, dendritic cells), and lymphoid lineages (T, B, and NK cells). The hematopoietic tissue contains a heterogenous population of cells with long-term and short-term regeneration capacities and committed multipotent, oligopotent, and unipotent progenitors. HSCs constitute 1:10,000 of cells in myeloid tissue. HSCs are critical for the repopulation of patients' blood cells in bone marrow transplantation.
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Macrophages (MΦ) are white blood cells produced by the differentiation of monocytes in tissues that have are phagocytic and antigen-presenting capacity. Macrophages function in both non-specific defense (innate immunity) as well as help initiate specific defense mechanisms (adaptive immunity) of vertebrate animals. Their role is to phagocytose (engulf and then digest) cellular debris, cancerous cells, and pathogens and also stimulate lymphocytes and other immune cells in response to pathogens. Macrophages can be identified by specific expression of a number of proteins including CD14, CD11b, F4/80 (mice)/EMR1 (human), MAC-1/MAC-3 and CD68 by flow cytometry or immunohistochemical staining.
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Extracellular Markers

Mast Cell

Mast cells are tissue resident cells that are most well-known for their role in allergy, autoimmunity, and anaphylaxis, but also have important roles in wound healing and pathogen defenses. Mast cells contain many granules full of inflammatory factors including histamine, heparin, and lipid mediators, such as thromboxane, prostaglandin D2, and leukotriene C4, as well as other factors. Mast cells degranulate upon stimulation by direct physical injury or chemical injury, cross-linking of Immunoglobulin E (IgE) receptors, or by activated complement proteins.

Extracellular Markers


Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of cells that have potent T cell-suppressive function, characterized by an activated state with increased production of reactive oxygen and nitrogen species, and arginase 1. In mice, the phenotype of MDSCs is CD11b+GR1+, while in humans, the phenotype of MDSCs is LIN-HLA-DR-CD33+ or CD11b+CD14-CD33+. Tumors have have been shown to hijack the suppressive capacity of MDSCs and use them to escape T cell killing, in order to promote tumor survival and expansion.


Megakaryocytes are blood cells that produce platelets (thrombocytes), which are required for normal blood clotting. In the bone marrow, megakaryocytes are quite rare, accounting for only 1 in 10,000 white blood cells. The primary signal for megakaryocyte production is thrombopoietin (TPO), although other factors can induce differentiation of progenitor cells in the bone marrow towards a final megakaryocyte phenotype, including GM-CSF, IL-3, IL-6, IL-11, chemokines (SDF-1 ; FGF-4), and erythropoietin. When the cell reaches megakaryoblast stage, it loses its ability to divide. However, it is still able to replicate its DNA and continue development, becoming polyploid, up to 64N, while the cytoplasm continues to expand.
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Extracellular Markers

Mesenchymal Stem Cell

Mesenchymal stem cells, or MSCs, are multipotent stem cells derived from the mesoderm that can differentiate into a variety of cell types, including: osteoblasts, chondrocytes, myocytes, adipocytes, and even β-pancreatic islet cells. While hematopoietic stem cells are also derived from the mesoderm, mesenchymal stem cells are committed to a non-hematopoietic path and cannot differentiate into blood cells. Due to their multipotency, MSCs are now widely studied to determine their possible utility in tissue engineering, wound healing, diabetes, and other conditions in which regenerated cells can improve or resolve disease.

Extracellular Markers


Microglia are considered to be the immune cells of the brain. They are the resident macrophages of the nervous system that engage in phagocytosis and clearing of damaged or dying neurons, infectious agents, and plaques. Microglia are also capable of producing proinflammatory cytokines and chemokines, and thus, are central to chronic neuroinflammation.

Extracellular Markers


Monocytes are circulating white blood cells which are able to patrol the body and populate specific tissues in response to environmental stimuli. Once in the tissue, they have the ability to differentiate into macrophages and dendritic cells. Monocytes can be divided into several subsets in both human and mouse. In mice, monocytes are typically classified as inflammatory monocytes (Ly6Chi, CCR2hi, CX3CR1low) which have pro-inflammatory and antimicrobial functions or patrolling monocytes (Ly6Clow, CCR2low, CX3CR1hi) which patrol the bloodstream and are involved in tissue repair. In humans, monocytes are classified based on their expression of CD14 and CD16 and named classical (CD14hi, CD16-), intermediate (CD14hi, CD16int), and non-classical (CD14lo/neg, CD16hi).
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Myeloid Dendritic Cell

Dendritic cells (DCs) are immune cells that function as antigen-presenting cells of the immune system, interacting with T cells and B cells to trigger and modulate the adaptive immune response. They act as messengers between the innate and adaptive immunity. Dendritic cells are present in tissues in contact with the external environment, such as the skin (where there is a specialized dendritic cell type called Langerhans cells) and the inner lining of the nose, lungs, stomach and intestines. They can also be found in an immature state in the blood, but migrate to lymph nodes where they stimulate T and B cells.
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Naïve T Cell

Naïve T cells are also known as resting T cells that circulate in the blood, waiting to be activated by antigen presenting cells. They are central to the adaptive immune response by providing stimulating signals and cytokines to effector cells such as CD8 cytotoxic T cells, B cells, or macrophages.
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Extracellular Markers


Neurons, or nerve cells, are cells capable of transmission of information through electrical and chemical signals. Neurons make up the nervous system, which consists of the brain, spinal cord, and ganglia. Unlike most cells, neurons do not undergo cell division and must be maintained by special stem cells.


Neutrophils are the most common cell type found in the blood, constituting a major part of the innate immune system. They are classified as granulocytes, along with basophils and eosinophils, and are often referred to as polymorphonuclear neutrophils (PMNs). They are typically the first responders to acute inflammation, such as bacterial infection, injury, or certain cancers.
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NK Cell

Natural killer cells (or NK cells) are a type of cytotoxic lymphocyte that are essential in the innate immune system. NK cells play a major role in the rejection of tumors and cells infected by viruses. They kill cells by releasing small cytoplasmic granules of proteins called perforin and granzyme that cause the target cell to die by apoptosis (programmed cell death). NK cells are derived from the common lymphoid progenitor generating B and T lymphocytes. NK cells express the surface markers CD16 (FcγRIII) and CD56 in humans, NK1.1 or NK1.2 in C57BL/6 mice, while they do not express T-cell antigen receptors (TCR) or Pan T marker CD3 or immunoglobulins (Ig) B cell receptors, which are found on T and B cells. Up to 80% of human NK cells also express CD8. They are distinct from Natural Killer T cells, which express CD3.
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Plasmacytoid Dendritic Cell

Plasmacytoid dendritic cells (pDCs) are innate immune cells that circulate in the blood and are found in peripheral lymphoid organs. In humans, pDCs express the surface markers CD123, BDCA-2(CD303) and BDCA-4(CD304), but do not express CD11c or CD14, which distinguishes them from conventional dendritic cells or monocytes, respectively. Mouse pDC express CD11c, B220, BST-2 (mPDCA) and Siglec-H and are negative for CD11b. Upon stimulation and subsequent activation, these cells produce large amounts of type I interferon, which are critical anti-viral compounds mediating a wide range of effects.
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Platelets, also known as thrombocytes, are made in the bone marrow, shedding from mature megakaryocytes in response to thrombopoetin. Because platelets are critical in forming blood clots, they are key to preventing excessive blood loss. Platelets also promote coagulation and wound healing by secreting a number of factors like PDGF and VEGF.

Stromal Cells

Stromal cells make up any connective tissue within an organ. Stromal cells consist of fibroblasts, myfibroblasts, endothelial cells, pericytes, smooth muscle cells, and mesenchymal stromal cells. The main role of these cells is to provide support to other functional cells located in these tissues. More recently, stromal cells have been found to be involved with persistence of cancer, pathogen response, antigen presentation, and wound healing.

T Follicular Helper

Tfh cells provide essential help to the production of affinity matured B cells in germinal centers. They are distinguishable from other T helper types by a number of criteria, including expression of the transcription factor Bcl-6 and CXCR5, the receptor for CXCL13 that recruits Tfh cells to follicles. Their function is also unique, in that they provide B cell help that is unlike that of Th2 cells by their production of IL-21, a helper cytokine that potently stimulates the differentiation of B cells into antibody-forming cells.


Th1 cells are IFN-γ + IL-12 polarized T helper cells that drive the killing efficacy of macrophages and proliferation of cytotoxic CD8 T cells in response to pathogens. They are characterized by the expression of the transciption factor T-bet and produce cytokines: IL-2, IFN-γ, and TNF.


Th2 cells are IL-4 polarized T helper cells that stimulate the humoral response to infections, including B cell proliferation, class-switching, and increased antibody production. They are characterized by the expression of the transciption factor GATA3 and produce cytokines: IL-4, IL-5, IL-6, IL-10, and IL-13.


Th9 cells are a recently characterized subset of T helper cells that play a role in protection against extracellular parasites, particularly nematodes. Th9 cells are polarized from naive cells via IL-4 and TGF-β. While they are distinct from Th2, Th9 cells can be derived from Th2 cells through the action of TGF-β. Despite producing anti-inflammatory IL-10, they are associated with inflammatory diseases such as allergic inflammation.

Intracellular Markers

Extracellular Markers


Th17 cells are a unique subset of activated T helper cells that normally provide anti-microbial immunity at epithelial and mucosal barriers. They are also implicated in a variety of autoimmune diseases. Th17 cells are characterized by their expression of intracellular RORγt and STAT3 and production of cytokines: IL-17A, IL-17F, IL-21 and IL-22. In humans, they can be identified using cell surface markers for CD4, CD161 and CCR6.


Th22 cells are a new subset of pro-inflammatory T helper cells whose normal function is yet to be fully defined, although they are suggested to be involved in skin immunity. They are implicated in a variety of autoimmune diseases, such as rheumatoid arthritis, Crohn's diseas, psoriasis, and atopic dermatitis. Although displaying some similarities to Th17 cells with cell surface receptors and the production of IL-22, Th22 cells are distinguished by their polarization by TNF-α, expression of the aryl hydrocarbon receptor and CCR10, and their lack of IL-17 production.

Intracellular Markers


T regulatory cells (also known as Tregs or Regulatory T cells) are essential cells in the immune system that suppress immune responses of other cells, designed to limit excessive reactions and prevent autoimmunity. Tregs are characterized by the expression of CD4, CD25, and Foxp3, while lacking CD127. CD4+Foxp3+ regulatory T cells have been referred to as "naturally-occurring" regulatory T cells to distinguish them from "suppressor" T cell populations that are generated in vitro. While other variants of suppressive T cells do exist, such as CD8 suppressor cells, Th3 and Tr-1 cells, Tregs are classically defined as CD4+CD25+FOXP3+ cells.

Intracellular Markers


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