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CD23

Wednesday 28 October 2009

HUGO:FCER2

PO WP

CD23 (FCER2 ) is a key molecule for B-cell activation and growth. It is a low affinity IgE receptor (Fc fragment of IgE receptor, FCERs). CD23 is 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. CD23 regulates IgE synthesis through CD21 and IgE binding and mediates IgE related immune responses.

CD21, CD23 and CD35 are dendritic cell markers.

Expression

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

Flow cytometry

- CD23 shows variability in flow cytometry expression between specimens from same patient.

Diagnosis

- CD21, CD23 and CD35 are dendritic cell markers.
- CD23 differentiate SLL/CLL (CD23+) vs. mantle cell lymphoma or MALT lymphoma (CD23-)
- CD23 is a B cell marker, particularly for SLL/CLL, mediastinal large B cell lymphoma and lymphoplasmacytic lymphoma.
- CD23 distinguishes nodal mantle cell lymphoma from follicular lymphoma by identifying a disrupted follicular dendritic cell pattern (Int J Surg Pathol 2005;13:73).

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)

Expression in tumors

- B-cell CLL/SLL (almost all cases; high levels, Leuk Res 2002;26:809, Hum Pathol 1999;30:648)
- Atypical cases of CLL/SLL may have higher levels (Am J Clin Pathol 2001;116:655)

- Follicular dendritic cell tumors (including inflammatory pseudotumor type, Am J Surg Pathol 2001;25:721)

- Diffuse large B cell lymphoma (DLBCL) (16%)
- Mediastinal large B cell lymphoma (70%, Histopathology 2004;45:619)

- Lymphoplasmacytic lymphoma (61%, usually dim intensity by flow cytometry, Am J Clin Pathol 2005;124:414, Clin Lymphoma 2005;5:246)
- Hairy cell leukemia (17%, Am J Clin Pathol 2006;125:251)

Negative staining

- Basophils, resting B cells
- Other B cell lymphomas including Burkitt lymphoma, Burkitt-like lymphoma (Am J Surg Pathol 2005;29:1652), follicular lymphoma, mantle cell lymphoma and marginal zone lymphoma (Am J Surg Pathol 1999;23:59, Mod Pathol 1998;11:967)
- Most T cell lymphomas,
- inflammatory fibroid polyps of the gastrointestinal tract (although of dendritic cell origin, Am J Surg Pathol 2004;28:107),
- follicular dendritic cell tumor and interdigitating dendritic cell tumor

See also

- CDs