CD38

Summary

CD38 helps mobilise intracellular calcium to activate a wide array of cell functions. In haematological cell types CD38 it is widely expressed by lymphoid cells B, T and NK) as well as myeloid precursor cells and mature myeloid cells.

CD38 has particular diagnostic importance for lymphocytes where CD38 expression is acquired as stem cells commit to B-cell lineage, then is lost as mature B cells emerge from bone marrow before being re-acquired at the time of plasma cell differentiation.

Normal expression and function

The wide expression of CD38 limits its diagnostic value except in very specific circumstances:

• The co-expression of CD38 with CD138 can identify normal or neoplastic plasma cells
• Expression of CD38 in chronic lymphocytic leukaemia (>20% of cells) may associated with poorer outcome

Other relevant information:

CD38 is a therapeutic target, daratumumab is a monoclonal antibody which binds to CD38 and is used in the treatment of myeloma.

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Expression in primitive cell types
AML	CMML	B ALL	BL	T ALL	ETP ALL	MPAL	Hgn
2-20%*	40-80%	40-80%	40-80%	40-80%	40-80%	40-80%	80-100%*

Notes: * expression correlates with subtype, particularly APML. Expression by haematogones is very high.

Expression in mature B cell neoplasms
CLL	MCL	FL	MZL	HCL	DLBCL	LPL	PCL
2-20%*	80-100%	80-100%	80-100%	2-20%	80-100%*	40-80%	80-100%**

Notes: Expression level in CLL and DLBCL may have prognostic value, plasma cells express the marker fairly consistently although the levels can vary.

Expression in mature T cell neoplasms
ATLL	CTCL/Sezary	T-PLL	T-LGL	NK-LGL
80-100%	80-100%	80-100%	80-100%	80-100%

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