CD13

Normal expression and function

CD13 is an enzyme which cleaves eutral amino acids from the N terminus of small peptides. The function of CD13 appears to vary with the tissue and the precise function in myeloid cells is unclear. The pattern of expression that is similar to other pan-myeloid markers (CD117 and CD33), but with levels generally increasing during maturation (contrasting with CD33 whose expression decreases). Maturation of myeloid cells may be partly identified through the relative CD33/13 expression.

Diagnostic role

• Together with other markers (CD117, CD33 and MPO) CD13 identifies myeloid lineage, particularly acute myeloid leukaemia. CD13 is also found on myelomonocytic and monocytic leukaemias.

• Expression is often absent on more primitive AML, erythroid or megakaryoblastic AML

• Aberrant expression by ALL occurs in around 30% of patients (at the 20% threshold)

• Overall high sensitivity, but may be less specific than CD117 or MPO.

Other relevant information:

Outside the haematopoietic system CD13 is particularly expressed on small intestinal and renal tubular epithelial cells and synaptic membranes from the CNS.

---

---

SUMMARY TABLES

Expression of CD13 by cells with early differentiation: ALL and haematogones
pro-B ALL	early pre-B ALL	pre-B ALL	B-ALL	pro T-ALL	mat T-ALL	AML	Hgns
poss	poss	poss	rare	rare	rare	strg	freq

* 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
rare	rare	rare	rare	rare	rare	rare	rare

*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

SUMMARY TABLES

Expression by acute leukaemias and by haematogones

• Poss.png

  B lineage ALL

• Rare.png

  T lineage ALL

• Rare.png

  ETP ALL

• Hi.png

  AML

• Freq.png

  Haemato-gones

Notes

In ALL the expression of CD13 is more likely in B-ALL but is also seen in T-ALL

In AML CD13 is expressed in around 80% of cases

In haematogones expression of CD13 is very frequent

Expression by B-lymphoproliferative disorders

• Rare.png

  CLL

• Rare.png

  PLL

• Rare.png

  MCL

• Rare.png

  FL'

• Rare.png

  HCL

• Rare.png

  HCLv

• Rare.png

  MZL

• Rare.png

  LPL

• Rare.png

  PCs

---

CD13 expression: primitive cell types
B ALL	T ALL	AML	ETP ALL	MPAL	Hgns
rare	freq	strg	strg	freq	strg

CD13 expression: B cell neoplasms
CLL	MCL	FL	HCL	MZL	LPL	PCL
rare	rare	rare	rare	rare	rare	rare

---

KEY

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

Limited studies

Rare (<5%)

Possible (5-20%)

Likely (20-40%)

Frequent (40-80%)

Expected (80-100%)

---