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Protein FCER2 PDB 1t8c.png
Available structures
PDBOrtholog search: PDBe RCSB
AliasesFCER2, BLAST-2, CD23, CD23A, CLEC4J, FCE2, IGEBF, Fc fragment of IgE receptor II, FCErII, Fc epsilon receptor II
External IDsOMIM: 151445 MGI: 95497 HomoloGene: 1517 GeneCards: FCER2
RefSeq (mRNA)


RefSeq (protein)


Location (UCSC)Chr 19: 7.69 – 7.7 MbChr 8: 3.73 – 3.74 Mb
PubMed search[3][4]
View/Edit HumanView/Edit Mouse

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.[5]


CD23 is known to have a role of transportation in antibody feedback regulation. Antigens which enter the blood stream can be 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.[6]

Clinical significance

The allergen responsible in dust mite allergy Der p 1 is known to cleave CD23 from a cell’s 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).

Patterns of CD23 (and CD21) expression by the follicular dendritic cells in follicular lymphoma.[7]

In flow cytometry, CD23 is helpful in the differentiation of chronic lymphocytic leukemia (CD23-positive) from mantle cell lymphoma (CD23-negative).[8] CD23 can also be demonstrated in germinal centre follicular dendritic cells using immunohistochemistry but is minimally expressed by benign germinal center B cells. In contrast to neoplastic mantle cells (which are negative for CD23), the resting cells of physiologic mantle zone express CD23. Paradoxically, Lymphomas arising from the mantle zone are generally negative for CD23, while most B-cell chronic lymphomocytic leukaemias are positive, allowing immunohistochemistry to distinguish these conditions, which otherwise have a similar appearance. Reed–Sternberg cells are usually positive for CD23.[9]

See also


  1. ^ a b c GRCh38: Ensembl release 89: ENSG00000104921 - Ensembl, May 2017
  2. ^ a b c GRCm38: Ensembl release 89: ENSMUSG00000005540 - 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. ^ Lichtman AH, Abbas AK (2003). Cellular and molecular immunology. Philadelphia: Saunders. pp. 324–325. ISBN 0-7216-0008-5.
  6. ^ Henningsson F, Ding Z, Dahlin JS, Linkevicius M, Carlsson F, Grönvik KO, Hallgren J, Heyman B (2011). Metzger DW (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. Bibcode:2011PLoSO...621760H. doi:10.1371/journal.pone.0021760. PMC 3130775. PMID 21765910.
  7. ^ Kurshumliu F, Sadiku-Zehri F, Qerimi A, Vela Z, Jashari F, Bytyci S; et al. (2019). "Divergent immunohistochemical expression of CD21 and CD23 by follicular dendritic cells with increasing grade of follicular lymphoma". World J Surg Oncol. 17 (1): 115. doi:10.1186/s12957-019-1659-8. PMC 6610797. PMID 31269981.{{cite journal}}: CS1 maint: multiple names: authors list (link)
    - This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (
  8. ^ Barna G, Reiniger L, Tátrai P, Kopper L, Matolcsy A (Sep 2008). "The cut-off levels of CD23 expression in the differential diagnosis of MCL and CLL". Hematological Oncology. 26 (3): 167–70. doi:10.1002/hon.855. PMID 18381689. S2CID 20572446.
  9. ^ Cooper K, Leong AS (2003). Manual of diagnostic antibodies for immunohistology. London: Greenwich Medical Media. p. 95. ISBN 1-84110-100-1.

Further reading

External links

  • Human FCER2 genome location and FCER2 gene details page in the UCSC Genome Browser.
  • PDBe-KB provides an overview of all the structure information available in the PDB for Human Low affinity immunoglobulin epsilon Fc receptor