CD Markers

Author: Nat Pernick, M.D. (see Authors page)

Revised: 29 December 2015, last major update July 2013

Copyright: (c) 2002-2015,, Inc.

Related: CD1bCD1cCD1dCD1eCD1-General

Cite this page: CD1a. website. Accessed October 21st, 2016.
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
Micro Images
Langerhans cell histiocytosis:

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Ear (fig B)

Lung: right is bronchioalveolar lavage


Rib (fig 3)




Unknown site

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Thyroid gland

Unknown site


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Esophagus: Barrett's metaplasia

    Oral cavity: gingiva-normal and diseased

Skin: normal

Skin: mycosis fungoides

Thymus: normal

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