CD23

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Fc fragment of IgE, low affinity II, receptor for (CD23)
Protein FCER2 PDB 1t8c.png
PDB rendering based on 1t8c.
Available structures
PDB Ortholog search: PDBe, RCSB
Identifiers
Symbols FCER2 ; BLAST-2; CD23; CD23A; CLEC4J; FCE2; IGEBF
External IDs OMIM151445 MGI95497 HomoloGene1517 ChEMBL: 2940 GeneCards: FCER2 Gene
RNA expression pattern
PBB GE FCER2 206760 s at tn.png
PBB GE FCER2 206759 at tn.png
More reference expression data
Orthologs
Species Human Mouse
Entrez 2208 14128
Ensembl ENSG00000104921 ENSMUSG00000005540
UniProt P06734 P20693
RefSeq (mRNA) NM_001207019 NM_001253737
RefSeq (protein) NP_001193948 NP_001240666
Location (UCSC) Chr 19:
7.75 – 7.77 Mb
Chr 8:
3.68 – 3.69 Mb
PubMed search [1] [2]

CD23, also known as Fc epsilon RII, or FcεRII, is the "low-affinity" receptor for IgE, an antibody isotype involved in allergy and resistance to parasites, and is important in regulation of IgE levels. Unlike many of the antibody receptors, CD23 is a C-type lectin. It is found on mature B cells, activated macrophages, eosinophils, follicular dendritic cells, and platelets.

There are two forms of CD23: CD23a and CD23b. CD23a is present on follicular B cells, whereas CD23b requires IL-4 to be expressed on T-cells, monocytes, Langerhans cells, eosinophils, and macrophages.[1]

Function[edit]

CD23 is known to have a role of transportation in antibody feedback regulation. Antigen that enters the blood stream is captured by antigen specific IgE antibodies. The IgE immune complexes that are formed bind to CD23 molecules on B cells, and are transported to the B cell follicles of the spleen. The antigen is then transferred from CD23+ B cells to CD11c+ antigen presenting cells. The CD11c+ cells in turn present the antigen to CD4+ T cells, which can lead to an enhanced antibody response.[2]

Clinical significance[edit]

The allergen responsible in dust mite allergy Der-p-1 is known to cleave CD23 from a cells surface. As CD23 is soluble, it can move freely and interact with cells in plasma. Recent studies have shown that increased levels of soluble CD23 cause the recruitment of non-sensitised B-cells in the presentation of antigen peptides to allergen-specific B-cells, therefore increasing the production of allergen specific IgE. IgE, in turn, is known to upregulate the cellular expression of CD23 and Fc epsilon RI (high-affinity IgE receptor).

In flow cytometry, CD23 is helpful in the differentiation of chronic lymphocytic leukemia (CD23-positive) from mantle cell leukemia (CD23-negative).[3] CD23 can also be demonstrated in germinal centre B-cells using immunohistochemistry, but it is not present in the resting cells of the surrounding mantle zone. Lymphomas arising from the mantle zone are generally negative for CD23, but most B-cell chronic lymphomocytic leukaemias and low-grade B-cell lymphomas are positive, allowing immunohistochemistry to distinguish these conditions, which otherwise have a similar appearance. Reed-Sternberg cells are usually positive for CD23.[4]

References[edit]

  1. ^ Lichtman AH, Abbas AK (2003). Cellular and molecular immunology. Philadelphia: Saunders. pp. 324–325. ISBN 0-7216-0008-5. 
  2. ^ Henningsson F, Ding Z, Dahlin JS, Linkevicius M, Carlsson F, Grönvik KO, Hallgren J, Heyman B (2011). Metzger, Dennis W., ed. "IgE-Mediated Enhancement of CD4+ T Cell Responses in Mice Requires Antigen Presentation by CD11c+ Cells and Not by B Cells". PLoS ONE 6 (7): e21760. doi:10.1371/journal.pone.0021760. PMC 3130775. PMID 21765910. 
  3. ^ Barna G, Reiniger L, Tátrai P, Kopper L, Matolcsy A (September 2008). "The cut-off levels of CD23 expression in the differential diagnosis of MCL and CLL". Hematol Oncol 26 (3): 167–70. doi:10.1002/hon.855. PMID 18381689. 
  4. ^ Cooper K, Leong A S-Y (2003). Manual of diagnostic antibodies for immunohistology. London: Greenwich Medical Media. p. 95. ISBN 1-84110-100-1. 

Further reading[edit]

See also[edit]