CD Markers

Last author update: 1 August 2013
Last staff update: 24 August 2023

Copyright: 2002-2023,, Inc.

PubMed Search: CD8

Nat Pernick, M.D.
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Cite this page: Pernick N. CD8. website. Accessed November 28th, 2023.
Definition / general
  • Cytotoxic T cell marker (Wikipedia); CD8+ cells are called T cell suppressor cells, cytotoxic T cells
  • Also called OKT8
  • Cell surface glycoprotein, member of immunoglobulin superfamily; at 2p12
  • Heterodimer of an alpha (CD8A, OMIM #186910 ) and a beta chain (CD8B, OMIM #186730 ) linked by two disulfide bonds; each chain has significant homology to immunoglobulin variable light chains; is present as a heterodimer on thymocytes and as homodimer on peripheral blood T cells
  • Both the CD8 antigen (acting as a coreceptor) and the T cell receptor recognize antigens displayed by an antigen presenting cell (APC) in the context of class I MHC molecules; CD8 binds to non-polymorphic region of class I molecules; may increase avidity of interactions between cytotoxic T cell and target cell during antigen-specific activation
  • Can kill target cells by recognizing peptide-MHC complexes on them or by secreting cytokines capable of signaling through death receptors on target cell surface
  • CD8 alpha cells promote survival and differentiation of activated T cells into memory CD8+ T cells
  • CD8 T cell clonal expansions occurr in normal young (PLoS One 2011;6:e21240) and elderly adults (Immunol Rev 2005;205:170)
  • May contribute to initiation, progression and regulation of autoimmune responses (Curr Opin Immunol 2005;17:624)
Diagrams / tables

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CD8+ T cell activation requires 2 signals

Clinical features
Uses by pathologists
  • Marker of T cells (normal and malignant)
  • Marker of cytotoxic / suppressor T cells
  • Classify lymphomas
  • Differentiate splenic hamartoma (CD8+) from hemangioma or littoral cell angioma (CD8-)
  • Note: use of CD3, CD8 does NOT improve detection of gluten-sensitive enteropathy in duodenal biopsies (Mod Pathol 2013 Apr 5 [Epub ahead of print])
Microscopic (histologic) images

Case #179

Splenic littoral cell angioma, sinus lining cells are CD8-

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Bladder: follicular cystitis (fig D)

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Skin: cutaneous CD8+ epidermotropic T cell lymphoma

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Skin: lymphomatoid papulosis (fig B, C)

Positive staining - normal
  • Cortical thymocytes (70-80%), T cells (25-35% of mature peripheral T cells, mostly cytotoxic T cells), NK cells (30%) and dendritic cells
  • Splenid littoral cells but not littoral cell angioma (Arch Pathol Lab Med 2019;143:1093)
Positive staining - disease
Negative staining
  • Adult T cell leukemia / lymphoma, littoral cell hemangioma of spleen
Flow cytometry images

Case #36

Anaplastic large
cell lymphoma:
partial CD4 / CD8

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