CD103 (Hairy Cell Marker)

CD103 (integrin αE) is a cell-surface marker primarily used to identify tissue-resident lymphocytes—especially CD8+ tissue-resident memory T (TRM) cells—in epithelial and mucosal sites. It mediates adhesion to E-cadherin, promoting retention in skin, gut, and lung epithelia. CD103 is also expressed on certain dendritic cell subsets and intraepithelial lymphocytes.

Hairy cell leukemia characteristically expresses B‑cell markers CD19, CD20 and CD22 and classic hairy‑cell markers CD11c, CD25, CD103 and CD123. Annexin A1 and tartrate‑resistant acid phosphatase (TRAP) are typically positive. Many cases harbor the BRAF V600E mutation. Strong, bright expression of these markers on immunophenotyping helps distinguish hairy cell leukemia from other B‑cell disorders.

CD103 (integrin αEβ7) is primarily expressed on mucosal and epithelial-associated immune cells — notably intraepithelial lymphocytes and tissue-resident memory CD8+ T cells in gut, skin, and lungs. Subsets of regulatory T cells and specific antigen-presenting dendritic cells (e.g., gut CD103+ DCs) also express it, mediating retention via E‑cadherin binding and contributing to local immune surveillance.

Yes. Classic hairy cell leukemia is a B‑cell neoplasm that typically shows strong CD20 expression along with other B‑cell markers (CD19, CD22) and characteristic markers (CD11c, CD25, CD103). CD20 positivity underlies use of anti‑CD20 therapy (e.g., rituximab). Immunohistochemistry or flow cytometry confirms CD20 positivity for diagnosis and treatment planning.

CD103 is another name for integrin alpha E (αE), the protein encoded by the ITGAE gene. CD103 commonly pairs with integrin beta 7 to form the αEβ7 heterodimer, an adhesion molecule expressed on mucosal and tissue-resident T cells that binds E-cadherin on epithelial cells. It is used as a marker for tissue-resident memory T cells in research and diagnostics.

CD13 (aminopeptidase N) is expressed mainly on myeloid-lineage hematopoietic cells — neutrophils, monocytes, macrophages and subsets of dendritic cells — and on various nonhematopoietic tissues, including intestinal and renal proximal‑tubule epithelial cells, vascular endothelial and smooth muscle cells, fibroblasts and mesenchymal stromal cells. CD13 is also frequently found on bone marrow progenitors and is upregulated in many solid tumors.