CD23 (CLL Segregation Marker)

CD23 is the low‑affinity IgE receptor (FcεRII) expressed mainly on mature and activated B lymphocytes, some monocytes/macrophages and follicular dendritic cells. It indicates B‑cell activation and participates in IgE regulation, antigen presentation and immune regulation. In diagnostic labs, CD23 immunostaining helps distinguish chronic lymphocytic leukemia (CD23‑positive) from mantle cell lymphoma (typically CD23‑negative).

CD23 is the low‑affinity IgE receptor commonly expressed on CLL B cells. Strong surface CD23 positivity, along with CD5 and typical B‑cell markers (CD19/CD20), helps distinguish CLL from other B‑cell neoplasms, notably mantle cell lymphoma which is usually CD23‑negative. Soluble CD23 levels can reflect tumor burden and correlate with disease activity and prognosis.

Chronic lymphocytic leukemia immunophenotype: CD19+, CD5+, CD23+, CD20 dim/weak, surface immunoglobulin (sIg) weak, CD43+, CD200+, and CD79b weak; typically CD10– and FMC7–. CD38 expression is variable and used prognostically. These markers are identified by flow cytometry and help distinguish CLL from other B‑cell lymphoproliferative disorders. ZAP-70 is an intracellular prognostic marker often assessed separately.

Yes. Chronic lymphocytic leukemia (CLL) B cells typically express CD20, but expression is often weaker and more variable than on normal B cells. CLL cells are characteristically CD19+, CD5+, CD23+ with low surface immunoglobulin and reduced CD20 density, which can affect responses to anti‑CD20 monoclonal antibodies such as rituximab; newer agents may overcome low CD20 levels.

Follicular lymphoma is usually CD20+, CD10+ and BCL2/BCL6 positive; CD23 is typically negative. However, CD23 expression can be variable and may be detected in a minority of cases, often weak or focal. Therefore CD23 status alone is not diagnostic; interpretation should rely on the full immunophenotypic profile, morphology, and genetic findings.

CD23 (FcεRII) is primarily expressed on mature and activated B lymphocytes and on follicular dendritic cells. It is also found on activated monocytes and macrophages, certain dendritic-cell subsets, eosinophils, and some epithelial cells. CD23 expression can be upregulated by cytokines and immune activation, reflecting roles in IgE binding, antigen presentation, B‑cell regulation and modulation of allergic and inflammatory responses.