CD5: Difference between revisions
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Revision as of 19:32, 30 April 2023
- Summary
- This marker is expressed by normal T cells and a subset of normal B cells, however it main diagnostic role is in diagnosis of certain B cell disorders:
- In mature B cell neoplasms CD5 is used to indicate likely CLL or MCL (both have consistent expression of CD5)
- In acute lymphoblastic leukaemia CD5 is useful to indicate T lineage, with (relatively) low levels of aberrant expression
- It has low frequency of expression on other lymphoma types.
Normal expression and function
CD5 binds to the B-cell ligand CD72, and has a negative effect on T and B cell receptor signalling raising the threshold for response to antigen (possibly limiting responses to self-antigens). It is a pan T cell antigen (present on thymocytes and mature T cells) that is also expressed on a subset of B cells (B1 subset comprising around 10% of adult B cells, but with a wide range according to age and disease state). CD5 is expressed at higher level on T cells than B cells, and expression is increased on activation.
Diagnostic role
- CD5 is expressed by almost all cases of CLL/SLL and the majority of cases of mantle cell lymphoma (90%)
- However, CD5 can be expressed by marginal zone lymphoma (15%); lymphoplasmacytoid lymphoma (5-10%); and occasionally diffuse large B cell lymphomas (10%) (where it may be associated with poorer prognosis and Activated B Cell (ABC) subtype).
- CD5 is expressed by most mature T cell neoplasms (with the exception of hepatosplenic T Cell lymphoma and T cell large granular lymphocytic leukaemia).
- CD5 is useful in the diagnosis and classification of T cell acute lymphoblastic leukaemia (T-ALL) since it is positive in 90% of T-ALL, although expression may be dim or absent in early precursor T ALL.
Other relevant information:
Aberrant expression of CD5 by B-ALL (rare) or AML (around 10%) is described, but in both cases CD5 expression appears less common compared with other “ambiguous markers”.
SUMMARY TABLES
Expression in primitive cell types | ||||||
---|---|---|---|---|---|---|
AML | B ALL | Burkitt | T ALL | ETP ALL (i) | MPAL i | Hgns i |
5-20% | <5% | <5% | 40-80% | 40-80% DIM | 20-40% | 20-40% |
Notes: CD5 is a useful marker of T-lineage in acute leukaemia although not absolutely specific. Dim expression in ETP-ALL is useful dagnostically. It is also expressed on late stage haematogones
Expression in mature B cell neoplasms | |||||||
---|---|---|---|---|---|---|---|
CLL | MCL | FL | MZL | HCL | DLBCL | LPL | PCL |
80-100% | 80-100% | <5% | 5-20% | 5-20% | ? <5% 5-20% 20-40% 40-80% 80-100% | <5% | <5% |
Notes: xxxxx
Expression in mature T cell neoplasms* | ||||||
---|---|---|---|---|---|---|
ATLL | CTCL/Sezary | T-PLL | T-LGL | NK-LGL | ||
? <5% 5-20% 20-40% 40-80% 80-100% | ? <5% 5-20% 20-40% 40-80% 80-100% | ? <5% 5-20% 20-40% 40-80% 80-100% | ? <5% 5-20% 20-40% 40-80% 80-100% | ? <5% 5-20% 20-40% 40-80% 80-100% |
Notes: xxxxx
SUMMARY TABLES
Expression by acute leukaemias and by haematogones
- Rare.png
Pro-B ALL
- Rare.png
Early pre-B ALL
- Rare.png
Pre-B ALL
- Rare.png
Early B ALL
- Hi.png
Pro-T ALL *
- Hi.png
Mature-T ALL
- Poss.png
AML
- Poss.png
Haemato-gones *
* May be present on late haematogones * Weak CD5 is seen in early precursor T-ALL
Expression by B-lymphoproliferative disorders
- Hi.png
CLL
- Freq.png
PLL
- Hi.png
MCL
- Rare.png
FL
- Poss.png
HCL
- Poss.png
HCLv
- Poss.png
MZL
- Rare.png
LPL
- Rare.png
PCs
* occasionally described in FL
Expression by mature T-cell disorders
- Hi.png
T-PLL
- Hi.png
T-LGL
- Rare.png
NK-LGL
- Hi.png
ATLL *
- Hi.png
Sezary *
- Freq.png
Others **
* expression may be dim
** a range of other T cell disorders may circulate occasionally, marker expression varies