CD5 | |||||||||||||||||||||||||||||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| |||||||||||||||||||||||||||||||||||||||||||||||||||
Identifiers | |||||||||||||||||||||||||||||||||||||||||||||||||||
Aliases | CD5 , LEU1, T1, CD5 molecule | ||||||||||||||||||||||||||||||||||||||||||||||||||
External IDs | OMIM: 153340 MGI: 88340 HomoloGene: 7260 GeneCards: CD5 | ||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||
Wikidata | |||||||||||||||||||||||||||||||||||||||||||||||||||
|
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.
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.
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] : 67–69
The T-cell receptor (TCR) is a protein complex found on the surface of T cells, or T lymphocytes, that is responsible for recognizing fragments of antigen as peptides bound to major histocompatibility complex (MHC) molecules. The binding between TCR and antigen peptides is of relatively low affinity and is degenerate: that is, many TCRs recognize the same antigen peptide and many antigen peptides are recognized by the same TCR.
CD8 is a transmembrane glycoprotein that serves as a co-receptor for the T-cell receptor (TCR). Along with the TCR, the CD8 co-receptor plays a role in T cell signaling and aiding with cytotoxic T cell-antigen interactions.
ZAP-70 is a protein normally expressed near the surface membrane of lymphocytes. It is most prominently known to be recruited upon antigen binding to the T cell receptor (TCR), and it plays a critical role in T cell signaling.
B-lymphocyte antigen CD19, also known as CD19 molecule, B-Lymphocyte Surface Antigen B4, T-Cell Surface Antigen Leu-12 and CVID3 is a transmembrane protein that in humans is encoded by the gene CD19. In humans, CD19 is expressed in all B lineage cells. Contrary to some early doubts, human plasma cells do express CD19, as confirmed by others. CD19 plays two major roles in human B cells: on the one hand, it acts as an adaptor protein to recruit cytoplasmic signaling proteins to the membrane; on the other, it works within the CD19/CD21 complex to decrease the threshold for B cell receptor signaling pathways. Due to its presence on all B cells, it is a biomarker for B lymphocyte development, lymphoma diagnosis and can be utilized as a target for leukemia immunotherapies.
Tyrosine-protein kinase ITK/TSK also known as interleukin-2-inducible T-cell kinase or simply ITK, is a protein that in humans is encoded by the ITK gene. ITK is a member of the TEC family of kinases and is highly expressed in T cells.
Leukocyte surface antigen CD53 is a protein that in humans is encoded by the CD53 gene.
T-cell surface glycoprotein CD3 gamma chain is a protein that in humans is encoded by the CD3G gene.
Interferon-alpha/beta receptor beta chain is a protein that in humans is encoded by the IFNAR2 gene.
TYRO protein tyrosine kinase-binding protein is an adapter protein that in humans is encoded by the TYROBP gene.
1-Phosphatidylinositol-4,5-bisphosphate phosphodiesterase gamma-2 is an enzyme that in humans is encoded by the PLCG2 gene.
CD48 antigen also known as B-lymphocyte activation marker (BLAST-1) or signaling lymphocytic activation molecule 2 (SLAMF2) is a protein that in humans is encoded by the CD48 gene.
Killer cell immunoglobulin-like receptor 2DL1 is a protein that in humans is encoded by the KIR2DL1 gene.
Killer cell immunoglobulin-like receptor 2DL4 is a protein that in humans is encoded by the KIR2DL4 gene.
Protein tyrosine phosphatase non-receptor type 7 is an enzyme that in humans is encoded by the PTPN7 gene.
CD6 is a human protein encoded by the CD6 gene.
Killer cell immunoglobulin-like receptor 2DS4 is a protein that in humans is encoded by the KIR2DS4 gene.
Signal-regulatory protein beta-1 is a protein that in humans is encoded by the SIRPB1 gene. SIRPB1 has also recently been designated CD172B.
Cluster of differentiation CD79A also known as B-cell antigen receptor complex-associated protein alpha chain and MB-1 membrane glycoprotein, is a protein that in humans is encoded by the CD79A gene.
CD79b molecule, immunoglobulin-associated beta, also known as CD79B, is a human gene.
CD8a, is a human gene.