CD23

See: FCER2

Roles

 CD23 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).