CD5 (protein)

CD5[5] is a cluster of differentiation expressed on the surface of T cells (various species) and in a subset of murine B cells known as B-1a. The expression of this receptor in human B cells has been a controversial topic and to date there is no consensus regarding the role of this receptor as a marker of human B cells. B-1 cells have limited diversity of their B-cell receptor due to their lack of the enzyme terminal deoxynucleotidyl transferase (TdT) and are potentially self-reactive. CD5 serves to mitigate activating signals from the BCR so that the B-1 cells can only be activated by very strong stimuli (such as bacterial proteins) and not by normal tissue proteins. CD5 was used as a T-cell marker until monoclonal antibodies against CD3 were developed.

CD5
Available structures
PDBOrtholog search: PDBe RCSB
Identifiers
AliasesCD5, LEU1, T1, CD5 molecule
External IDsOMIM: 153340 MGI: 88340 HomoloGene: 7260 GeneCards: CD5
Gene location (Human)
Chr.Chromosome 11 (human)[1]
Band11q12.2Start61,102,489 bp[1]
End61,127,852 bp[1]
RNA expression pattern
More reference expression data
Orthologs
SpeciesHumanMouse
Entrez

921

12507

Ensembl

ENSG00000110448

ENSMUSG00000024669

UniProt

P06127

P13379

RefSeq (mRNA)

NM_014207
NM_001346456

NM_007650

RefSeq (protein)

NP_001333385
NP_055022

NP_031676

Location (UCSC)Chr 11: 61.1 – 61.13 MbChr 19: 10.72 – 10.74 Mb
PubMed search[3][4]
Wikidata
View/Edit HumanView/Edit Mouse

In humans, the gene is located on the long arm of chromosome 11. There is no confirmed ligand for CD5 but there is evidence that CD72, a C-type lectin, may be a ligand or that CD5 may be homophilic, binding CD5 on the surface of other cells.[6] CD5 includes a scavenger receptor cysteine-rich protein domain.

T cells express higher levels of CD5 than B cells. CD5 is upregulated on T cells upon strong activation. In the thymus, there is a correlation with CD5 expression and strength of the interaction of the T cell towards self-peptides.

Immunohistochemistry

CD5 is a good immunohistochemical marker for T-cells, although not as sensitive as CD3. About 76% of T-cell neoplasms are reported to express CD5, and it is also found in chronic lymphocytic leukemia and mantle cell lymphoma (both being B cell malignancies), that do not express CD3. It is commonly lost in cutaneous T-cell lymphoma, and its absence can be used as an indicator of malignancy in this condition. The absence of CD5 in T cell acute lymphoblastic leukemia, while relatively rare, is associated with a poor prognosis.[7]

References
  1. GRCh38: Ensembl release 89: ENSG00000110448 - Ensembl, May 2017
  2. GRCm38: Ensembl release 89: ENSMUSG00000024669 - Ensembl, May 2017
  3. "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  4. "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  5. "Entrez Gene: CD5 CD5 molecule".
  6. Brown MH, Lacey E (Nov 15, 2010). "A ligand for CD5 is CD5". Journal of Immunology. 185 (10): 6068–74. doi:10.4049/jimmunol.0903823. PMC 2996635. PMID 20952682.
  7. Leong, Anthony S-Y; Cooper, Kumarason; Leong, F Joel W-M (2003). Manual of Diagnostic Cytology (2 ed.). Greenwich Medical Media, Ltd. pp. 67–68. ISBN 1-84110-100-1.

Further reading


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