Stains & CD markers

Last author update: 1 July 2013
Last staff update: 10 January 2022

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Related: CD1bCD1cCD1dCD1eCD1-general

Nat Pernick, M.D.
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Cite this page: Pernick N. CD1a. website. Accessed June 1st, 2023.
Definition / general
  • T cell surface antigen (gene on #1q22-23, not MHC linked)
  • CD1a+ T cells are normal component of T cell repertoire (Nat Immunol 2010;11:1102), important in dendritic cell presentation of glycolipids and lipopeptide antigens, particularly those that traffic through early endocytic and recycling pathways (J Immunol 2010;184:1235)
  • Also called Leu6
  • Activin A, a TGFβ family member induced by pro-inflammatory cytokines and involved in skin morphogenesis and wound healing, induces the differentiation of human monocytes into Langerhans cells in absence of TGFβ (PLoS One 2008;3:e3271)
Clinical features
Uses by pathologists
Microscopic (histologic) images

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Langerhans cell histiocytosis:
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Lung: right is bronchioalveolar lavage

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Esophagus: Barrett metaplasia

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Oral cavity: gingiva - normal and diseased

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Skin: mycosis fungoide

Cytology images

Case #72

Langerhans cell histiocytosis:

Skull - cytology

Positive staining - normal
  • Cortical thymocytes
  • Immature dendritic cells (Langerin-, CD86-, HLA-DR low, CD40 low)
  • Indeterminate cells (resemble Langerhans cells but no Birbeck granules on EM)
  • Langerhans cells (Langerin+, CD86+)
Positive staining - not malignant
Positive staining - tumors
Negative staining
  • B cells, follicular dendritic cells
  • Dendritic cells in most cutaneous B cell lymphomas (or weak staining, Am J Clin Pathol 2001;116:72), dendritic cell neurofibroma, Erdheim-Chester disease, follicular dendritic cell tumor, histiocytic lymphoma / sarcoma, histiocytoma, interdigitating dendritic cell sarcoma, juvenile xanthogranuloma, sinus histiocytosis with massive lymphadenopathy
  • PECOmas: CD1a negative, but may show aberrant cytoplasmic staining due to endogenous biotin (Hum Pathol 2011;42:369); prior report of CD1a+ PEComas at Pathol Int 2008;58:169
Electron microscopy images

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Langerhans cell histiocytosis: Birbeck granules

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