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]
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.[2]
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 lymphoma (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]
↑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. PMID18381689.
↑Cooper K, Leong AS (2003). Manual of diagnostic antibodies for immunohistology. London: Greenwich Medical Media. p. 95. ISBN1-84110-100-1.
Kijimoto-Ochiai S (Apr 2002). "CD23 (the low-affinity IgE receptor) as a C-type lectin: a multidomain and multifunctional molecule". Cellular and Molecular Life Sciences : CMLS. 59 (4): 648–64. doi:10.1007/s00018-002-8455-1. PMID12022472.
Schwarzmeier JD, Hubmann R, Düchler M, Jäger U, Shehata M (Feb 2005). "Regulation of CD23 expression by Notch2 in B-cell chronic lymphocytic leukemia". Leukemia & Lymphoma. 46 (2): 157–65. doi:10.1080/10428190400010742. PMID15621797.
Maekawa N, Kawabe T, Sugie K, Kawakami T, Iwata S, Uchida A, Yodoi J (May 1992). "Induction of Fc epsilon RII/CD23 on PHA-activated human peripheral blood T lymphocytes and the association of Fyn tyrosine kinase with Fc epsilon RII/CD23". Research in Immunology. 143 (4): 422–5. doi:10.1016/S0923-2494(05)80075-6. PMID1387715.
Maekawa N, Kawabe T, Sugie K, Kawakami T, Maeda Y, Uchida A, Yodoi J (1992). "Induction of Fc epsilon RII/CD23 on PHA-activated human peripheral blood T lymphocytes and association of fyn tyrosine kinase with Fc epsilon RII/CD23". International Journal of Tissue Reactions. 14 (3): 121–30. PMID1446976.
Yokota A, Kikutani H, Tanaka T, Sato R, Barsumian EL, Suemura M, Kishimoto T (Nov 1988). "Two species of human Fc epsilon receptor II (Fc epsilon RII/CD23): tissue-specific and IL-4-specific regulation of gene expression". Cell. 55 (4): 611–8. doi:10.1016/0092-8674(88)90219-X. PMID2972386.
Aubry JP, Pochon S, Gauchat JF, Nueda-Marin A, Holers VM, Graber P, Siegfried C, Bonnefoy JY (Jun 1994). "CD23 interacts with a new functional extracytoplasmic domain involving N-linked oligosaccharides on CD21". Journal of Immunology. 152 (12): 5806–13. PMID7515913.
Lecoanet-Henchoz S, Gauchat JF, Aubry JP, Graber P, Life P, Paul-Eugene N, Ferrua B, Corbi AL, Dugas B, Plater-Zyberk C (Jul 1995). "CD23 regulates monocyte activation through a novel interaction with the adhesion molecules CD11b-CD18 and CD11c-CD18". Immunity. 3 (1): 119–25. doi:10.1016/1074-7613(95)90164-7. PMID7621072.
Maruyama K, Sugano S (Jan 1994). "Oligo-capping: a simple method to replace the cap structure of eukaryotic mRNAs with oligoribonucleotides". Gene. 138 (1–2): 171–4. doi:10.1016/0378-1119(94)90802-8. PMID8125298.
Padlan EA, Helm BA (1994). "Modeling of the lectin-homology domains of the human and murine low-affinity Fc epsilon receptor (Fc epsilon RII/CD23)". Receptor. 3 (4): 325–41. PMID8142907.
Trask B, Fertitta A, Christensen M, Youngblom J, Bergmann A, Copeland A, de Jong P, Mohrenweiser H, Olsen A, Carrano A (Jan 1993). "Fluorescence in situ hybridization mapping of human chromosome 19: cytogenetic band location of 540 cosmids and 70 genes or DNA markers". Genomics. 15 (1): 133–45. doi:10.1006/geno.1993.1021. PMID8432525.
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Frémeaux-Bacchi V, Bernard I, Maillet F, Mani JC, Fontaine M, Bonnefoy JY, Kazatchkine MD, Fischer E (Jul 1996). "Human lymphocytes shed a soluble form of CD21 (the C3dg/Epstein-Barr virus receptor, CR2) that binds iC3b and CD23". European Journal of Immunology. 26 (7): 1497–503. doi:10.1002/eji.1830260714. PMID8766552.
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