CD38

DETAILS

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. It 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.

What is its diagnostic role?

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	Burkitt	T ALL	ETP ALL <I>	MPAL <I>	Hgns <I>
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
<5%	<5%	<5%	<5%	<5%	<5%	<5%	<5%

Notes: Low level expression has been reported on activated lymphocytes, but it has no definite diagnostic role

Expression in mature T cell neoplasms
ATLL	CTCL/Sezary	T-PLL	T-LGL	NK-LGL
<5%	<5%	<5%	<5%	<5%

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SUMMARY TABLES

Expression of CD38 by primitive lymphoid cells: ALL and haematogones
pro-B ALL	early pre-B ALL	pre-B ALL	B-ALL	pro-T ALL	mature-T ALL	AML	Haematogones
						*	stg

* low expression correlates with subtype e.g. APML

Expression of CD38 by mature B cells: B-lymphoproliferative disorders
CLL	MCL	FL	HCL	HCv	MZL	LPL	PCL
*		**					stg/mod

*May indicate adverse prognostic when present on more than 20% of cells

**May be weak

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1. Colour key: - the likelihood of any individual case expressing this marker, indicated by colour:

Rare (<5%)

Possible (5-20%)

Likely (20-40%)

Frequent (40-80%)

Expected (80-100%)

2. Text key: - where expression level is characteristic of a disorder this is indicated by text:

abs = absent expression, wk = weak expression, mod = moderate expression, stg = strong expression, sub = expression may be on a sub-population of cells