In dermatology, epithelium is a tissue composed of a layer of cells. In humans, it is one of four primary body tissues. Epithelium lines both the outside (skin) and the inside cavities and lumen of bodies. The outermost layer of our skin is composed of dead stratified squamous epithelial cells, as are the mucous membranes lining the inside of mouths and body cavities. Other epithelial cells line the insides of the lungs, the gastrointestinal tract, the reproductive and urinary tracts, and make up the exocrine and endocrine glands.

Epithelial tissues come in three basic types: squamous, cuboidal and columnar. These three types of tissue are seen in either simple (only one cell layer thick) or stratified (many cells in thickness) arrangements. Functions of epithelial cells include secretion, absorption, protection, transcellular transport, sensation detection, and selective permeability.  Endothelium (the inner lining of blood vessels) is a specialized form of epithelium.

1F3

• a new marker for renal epithelial cell injury. PMID: 9031272

4G10.3

• a biochemical and immunological marker of limbal basal cells, hypothesized to be corneal epithelial stem cells. PMID: 1730535

A6 antigen

• a differentiation marker of epithelial and erythroid cell lineages in early development of the mouse. PMID: 8299877

A33 antigen

• a definitive marker for basolateral surfaces of intestinal epithelial cells. PMID: 10960348

Adenosine 5'-Triphosphatase

• Cell surface adenosine 5'-triphosphatase (ecto-ATPase ) as an in vitro marker of the lineage and cytodifferentiation of oncogenic epithelial cells from rat liver parenchyma. PMID: 6244092

Aminopeptidase N

• a marker for the apical pole of porcine thyroid epithelial cells in vivo and in culture. PMID: 6119156

APN/CD13

• an epithelial-mesenchymal marker in skin. PMID: 12823446

AUA1

• a reliable immunocytochemical marker for detecting epithelial cells in body fluids. Its use improves diagnostic accuracy of morphological assessment in difficult cases. PMID: 1577978

BerEP4 (Ber-EP4)

• an epithelial-specific antibody. PMID: 10353728

beta-Crystallin

• a specific marker for detecting lentoidogenesis in cultures of chicken lens epithelial cells. PMID: 7832826

BG8 (Lewis Y blood antigen)

• a blood group related antigen. PMID: 15690338

Bmi-1 oncoprotein

• regulates proliferation and oncogenesis in human cells. Its overexpression leads to senescence bypass in human fibroblasts and immortalization of human mammary epithelial cells. PMID: 16778197

BRCA1

• localized in basal and/or luminal epithelial cells in noncancerous outgrowth cultured from breast organoids. BRCA1 immunofluorescence was detected for the most part in cell nuclei of the epithelial outgrowth when using confocal microscopy. PMID: 10639738

BTEB1

• expressed in a human endometrial epithelial cell line Hec-1-A. PMID: 11953011

CA-125

• expressed in normal epithelial tissues. PMID: 8235310
• serum CA125 level may correlate with the proliferative activity of epithelial cells in endometriotic lesions. PMID: 10993101

Calcyclin

• a marker of human epithelial cells and fibroblasts. PMID: 1572406

CAR-5

• a marker of colorectal epithelial cells. PMID: 1692551

Carcinoembryonic Antigen (CEA)

• an epithelial differentiation antigen. PMID: 1376008
• recognizing epithelial cell surface determinants for their ability to inhibit the collagen binding of SW1222 cells. PMID: 2304917

Cathepsin E (CaE)

• an aspartic proteinase, marker of normal gastric superficial/foveolar epithelial cells. PMID: 8078803

CC10 (Clara cell-specific protein)

• cell-specific marker of airway Clara cells. PMID: 9070353

Cystatin C

• present in proximal tubular epithelial cells of all kidney specimens. PMID: 7665147

Cytokeratins

• markers of epithelial cell differentiation: expression in normal epithelia. PMID: 1383915

Cytokeratin-8 (CK8)

• CK 8 antisense probe was accumulated only within prostatic epithelial cells. PMID: 7536487

Cytokeratins 8, 14, 18, and 19

• markers of prostate epithelial cell differentiation. PMID: 12520542

Cytokeratin-18 (CK18)

• epithelial-specific intermediate filament. PMID: 16507409
• The detection of CK18 neoepitope M30 in the serum might be a useful marker in tracing apoptotic epithelium in septic patients. PMID: 15316390

Cytokeratin-19

• a marker of neoplastic progression of human prostate epithelial cells. PMID: 9582089

Connexin-43 (Cx43)

• Cx43 was strongly expressed in the corneal and limbal suprabasal epithelial cells, but the basal cells of the limbal epithelium were negative. Cx43 antibody stained mainly large cells but not small cells in primary limbal epithelial cultures. PMID: 16424398

Desmin

• appears to be a promising marker for the distinction between reactive mesothelium and malignant epithelial cells in terms of both specificity and sensitivity, and its complementary use with calretinin is recommended. PMID: 11684957

EMA

• Epithelial membrane antigen. PMID: 3303592

Exo-1 (Pa-G14)

• represents a novel common antigen for normal and tumorous glandular epithelial cells. PMID: 3828998

EZH2

• a marker of aggressive breast cancer and promotes neoplastic transformation of breast epithelial cells. PMID: 14500907

Ezrin

• a glomerular epithelial cell marker, specifically expressed in glomerular epithelial cells in developing glomeruli in mature glomeruli and in glomerular epithelial cells in culture. PMID: 9853258

Foxa1

• a member of the winged helix family of transcription factors that is expressed in epithelial cells of the conducting airways and in alveolar type II cells of the lung. PMID: 16214823

GABRP

• specifically expressed in alveolar epithelial type II cells (AEC II), could be used as potential AEC II marker for studying lung epithelial cell biology and monitoring lung injury. PMID: 15184050

Galectin-3

• galectin-3-reactive ligands in squamous cancer and normal epithelial cells as a marker of differentiation. PMID: 11408923

GGT (gamma-glutamyl transpeptidase)

• Expressed in normal and neoplastic epithelial cells of human skin, and may be useful as a histochemical marker for distinguishing malignant tumours from benign epithelial tumours in human skin. PMID: 2870734

Glutamine Synthetase

• the first 3 months of gestation glutamine synthetase immunoreactivity is located exclusively in the retinal pigment epithelial (RPE). During the 3rd month the marker enzymes of the blood-retina barrier begin to appear. From the 4th month on, RPE cells are glutamine synthetase immunonegative. PMID: 10943675

H4

• a unique immunohistochemical marker of epithelium cells under normal and malignant growth conditions. PMID: 1384781

HLA-DR

• HLA-DR antigens were not expressed in the normal control mucosa or in the normal areas, and only on the epithelia of the polyp in 5 out of 7 specimens (71%). PMID: 2558037
• In normal cervical epithelium no HLA-DR staining was detected. HLA-DR was expressed by epithelial cells in six out of the 14 samples of wart virus infection. PMID: 2030146

HME1

• a novel epithelial cell marker protein. PMID: 1390337

Keratin 5 (K5)

• expressed in normal mammary epithelial cells in culture and are absent from tumor-derived cell lines. PMID: 1690428

Keratins 13 and 19

• a useful marker of odontogenic epithelium in general. PMID: 2465398

KL-6

• a lung epithelial cell marker, prominently expressed on the surface membrane of alveolar type II cells when these cells are proliferating, stimulated, and/or injured. PMID: 12959931

Lactoferrin

• a protein marker of myeloid and mammary epithelial secretory cell differentiation. PMID: 833425

LAMP-1 (lysosomal-associated membrane protein 1)

• a novel differentiation marker for HC11 mouse mammary epithelial cells. PMID: 8983177

Lectins

• markers of rumen epithelial cell differentiation. UEA-I reacted strongly with differentiated rumen epithelial cells both from rumen tissue and cell cultures and therefore appears to be a good general marker for rumen epithelial cell differentiation. PMID: 8206789

Leu-7

• a marker of subcapsular epithelial cells. PMID: 1692164

LhS28

• reacts with basal bodies of ciliated epithelial cells. PMID: 10560355

Ly110

• a new marker for the subpopulation of CDR1(+) or 6C3(+) epithelial cells in the neonatal and adult thymus and is useful for the studies on the epithelial cell differentiation process. PMID: 15777949

M1

• a mucin antigen, marker of normal gastric superficial/foveolar epithelial cells. PMID: 8078803

MBEC

• murine bile duct epithelial cell marker. PMID: 10094941

MEP-1

• After injury, a remarkable loss of pan-cadherin immunoreactivity in the MEP-1-positive type I epithelial cells was detectable. These findings suggest that characterization of normal alveolar epithelial cells and monitoring of the epithelial remodelling in pulmonary pathohistology are sufficiently described by the antibodies MEP-1 anti pancadherin. PMID: 8720458

MEP7

• Mouse epididymal protein 7 (MEP 7) was localized initially within the supranuclear regions of some principal epithelial cells in the proximal corpus while other cells remained unstained. PMID: 1591332

MOC-31

• an anti-epithelial marker. PMID: 11422496

NSE (neuron-specific enolase)

• represented a marker of most epithelial cells located in the medulla. PMID: 11083467

Neutral Aminopeptidase

• a potential marker enzyme of the amphibian urinary bladder epithelial cell apical membrane. PMID: 2572290

Normal Epithelial Cell Specific-1 (NES1)/kallikrein-10

• expressed in normal mammary and prostate epithelial cells. PMID: 11705853

P2X7

• specifically expressed in alveolar epithelial type I cells (AEC I), could be used as potential AEC I marker for studying lung epithelial cell biology and monitoring lung injury. PMID: 15184050

p16

• a marker of dysplastic and neoplastic alterations in cervical epithelial cells. PMID: 15339339

p16 (INK4A)

• a specific marker for dysplastic and neoplastic epithelial cells of the cervix uteri. PMID: 11291057

p63

• an especially useful marker of myoepithelial cells with naked nuclei in epithelial-myoepithelial carcinoma (EMC). PMID: 15959915

P-Cadherin

• a member of the cadherin family of cell surface glycoproteins that mediate Ca2+-dependent cell-cell adhesion and is expressed in a differential fashion in normal epithelial tissues. PMID: 9815605

Prostate Derived Factor (PDF)

• a member of transforming growth factor-beta (TGF-beta) superfamily proteins involved in differentiation of the prostate epithelium. PMID: 12520542

PHM-5

• directed against human glomerular epithelial cells, detect a human-specific cell surface carbohydrate antigen not previously described, and can be used to identify epithelial cells in renal biopsy sections and in culture outgrowths of isolated glomeruli. PMID: 6339971

PR1A3

• non-mucus-secreting columnar-epithelium-specific MAb. PMID: 1383164

PR5D5

• mucus-secreting colonic-epithelium-specific MAb. PMID: 1383164

Prominin-1 (CD133)

• a pentaspan membrane protein found on membrane protrusions of the apical surface of neuroepithelial cells. PMID: 15976444
• a novel marker for human prostatic epithelial stem cells. PMID: 15226377

Prostate Antigen (PA)

• a marker for human prostate epithelial cells. PMID: 6935463

Protein Gene Product 9.5(PGP 9.5)

• a new marker for parietal epithelial cells of Bowman's capsules, in anti-glomerular basement membrane(GBM) antibody induced glomerulonephritis of WKY rats. PMID: 11218314
• found exclusively in a subtype of cortical epithelial cells, located mostly within the inner zone of the cortex. PMID: 11083467

Prostatic Binding Protein (PBP)

• an androgen-dependent marker for prostate epithelial cells. PMID: 6998468

PSCA (Prostate stem cell antigen)

• a marker of late intermediate prostate epithelial cells. PMID: 12496358

Rab13

• localized to the junctional complex region of a variety of epithelia, including intestine, kidney, liver, and of endothelial cells. PMID: 8294494

RAGE

• the highly selective differentiation marker of human alveolar epithelial type I cells. PMID: 16315007

RLA (rat liver antigen)

• an epithelial cell marker. PMID: 2465398

Rex-1 (zinc-finger protein-42, Zfp42)

• detected in normal human epidermal keratinocytes, normal prostate epithelial cells (PrEC), bronchial, and small airway lung epithelial cells. PMID: 16865673

RTE 1, 2, 3, 7, 9 11, 12, 13

• Monoclonal antibody (Mab) markers for subpopulations of rat tracheal epithelial (RTE) cells. PMID: 1378386

RTI40

• a type I cell-specific protein is a biochemical marker of epithelial injury in a rat model of pneumonia. PMID: 7864138
• a differentiation marker of type I alveolar epithelial cells. PMID: 9761764

Secretory Component (SC)

• a glandular epithelial cell marker. PMID: 6271014

SPA, SPB, SPC (surfactant proteins A, B, C)

• epithelial cell-specific markers. PMID: 9564884

SPRR1B

• terminal differentiation marker, expression in various BE cells. PMID: 11313996

SQM1 protein

• a useful marker for the study of squamous differentiation and metaplasia of human bronchial epithelial (HBE) cells. PMID: 9509300

Sucrase-isomaltase (SI)

• a marker of foetal and malignant epithelial cells of the human colon. PMID: 6352518

Surfactant protein C (SPC)

• cell-specific marker of alveolar type II cells. PMID: 9070353

Thioesterase II

• a rat mammary epithelial cell-specific marker. PMID: 6196118
• a new marker enzyme for human cells of breast epithelial origin. PMID: 6589427

Transthyretin

• present in proximal tubular epithelial cells of all kidney specimens. PMID: 7665147

VAT-1

• a calcium-regulated activation marker of human epithelial cells. PMID: 12898150

Vimentin

• present in epithelial cells of the tonsil crypt. PMID: 8928645

Other Epithelial Cell Markers

• Glycocalyceal bodies--a marker for different epithelial cell types in human airways. PMID: 3599129
• Monoclonal antibodies recognize a cell surface marker of epithelial differentiation in the rabbit reproductive tract. PMID: 3543336
• Species differences in lectin binding to pulmonary cells: Soybean agglutinin (SBA) as a marker of type I alveolar epithelial cells and alveolar macrophages in mini pigs. PMID: 7518176
• Apical membrane marker is expressed early in colonic epithelial cells. PMID: 2962680
• Electrophoretic marker of differentiated human prostate secretory epithelial cells. PMID: 3703743
• A secreted phosphoprotein marker for neoplastic transformation of both epithelial and fibroblastic cells. PMID: 6835406
• Epithelial stem cells in the skin: definition, markers, localization and functions. PMID: 10206725
• Cytoskeletal markers allowing discrimination between brush cells and other epithelial cells of the gut including enteroendocrine cells. PMID: 8781995