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 major use is to combine CD38 with CD138 where co-expression identifies normal or neoplastic plasma cells

• CD38 may also be expressed in chronic lymphocytic leukaemia where expression on >20% has been associated with poorer outcome, although it is not widely used as a progostic marker

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.

---

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

---

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