CD23

Also known as low affinity IgE receptor, Fc fragment of IgE receptor, FCER

A type C lectin that can be secreted

After physiologic germinal cell development, the follicular dendritic cell meshwork expands and follicular dendritic cells in the light zone of the germinal center become CD23 positive

CD23 acts as a B cell growth and activation factor, promoting differentiation into plasma cells

Regulates IgE synthesis through CD21 and IgE binding (J Exp Med 2005;202:751), and mediates IgE related immune responses (Clin Rev Allergy Immunol 2005;29:61)

Shows variability in flow cytometry expression between specimens from same patient (AJCP 2002;117:615)

CD21, CD23 and CD35 are dendritic cell markers

High expression on B cells in peripheral blood is associated with bullous pemphigoid (J Dermatol Sci 2004;35:53)

CD23 antibodies may decrease adherence of Plasmodium falciparum-infected erythrocytes (Cell Microbiol 2004;6:839)

Mantle cell lymphoma: usually CD23 negative, but rarely/often has CD23 present with dim intensity by flow cytometry, AJCP 2003;120:760 / AJCP 2001;116:893; CD23+ mantle cell cases have high cyclin D1 levels, AJCP 2002;117:237); rarely has CD23+ cells in peripheral blood (AJCP 2002;118:758)

Uses: differentiate SLL/CLL (CD23+) vs. mantle cell lymphoma or MALT lymphoma (CD23-); B cell marker, particularly for SLL/CLL, mediastinal large B cell lymphoma and lymphoplasmacytic lymphoma; distinguish nodal mantle cell lymphoma from follicular lymphoma by identifying a disrupted follicular dendritic cell pattern (Int J Surg Pathol 2005;13:73), may identify prognostically favorable cases of diffuse large B cell lymphoma (Clin Cancer Res 2003;9:722), high soluble CD23 is associated with aggressive disease and poorer prognosis in CLL (Leuk Lymphoma 2002;43:549, Clin Lab Haematol 2006;28:30)

Micro images: angioimmunoblastic T cell lymphoma (figure F: CD23 highlights extrafollicular meshworks of follicular dendritic cells); CD23 negative MALT lymphoma with CD23+ follicular centers; CD23 negative mantle cell lymphoma with CD23+ follicular center

contributed by Leica Microsystems, Biosystems Division: normal tonsil; follicular lymphoma

Positive staining (normal): activated mature B cells expressing IgM or IgD (particularly mantle cells), activated monocytes / macrophages, T cell subsets, platelets, eosinophils, Langerhans cells, follicular dendritic cells, intestinal epithelium (encodes IgE receptor, Gastroenterology 2005;129:928)

Positive staining (disease): B-cell CLL/SLL (almost all cases; high levels, Leuk Res 2002;26:809; atypical cases may have higher levels, AJCP 2001;116:655); follicular dendritic cell tumors (including inflammatory pseudotumor type- AJSP 2001;25:721), mediastinal large B cell lymphoma (70%, Histopathology 2004;45:619), lymphoplasmacytic lymphoma (61%, usually dim intensity by flow cytometry, AJCP 2005;124:414, Clin Lymphoma 2005;5:246), hairy cell leukemia (17%, AJCP 2006;125:251), diffuse large B cell lymphoma (16%),

Negative staining: other B cell lymphomas including Burkitt’s lymphoma, Burkitt-like lymphoma (AJSP 2005;29:1652), follicular lymphoma, mantle cell lymphoma, marginal zone lymphoma (AJSP 1999;23:59, Mod Path 1998;11:967); also most T cell lymphomas, inflammatory fibroid polyps of the gastrointestinal tract (although of dendritic cell origin, AJSP 2004;28:107), follicular dendritic cell tumor, interdigitating dendritic cell tumor

References: OMIM 151445, Hum Path 1999;30:648 (early study)