CD5: Difference between revisions
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:<span style="color:navy">'''Summary'''</span> | :<span style="color:navy">'''Summary'''</span> | ||
: | :Although principally a T-cell antigen, the main diagnostic role of CD5 is in diagnosis of B cell disorders: | ||
*For 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 | |||
*This marker is expressed by normal T cells and a subset of normal B cells, and is found with low frequently on other lymphoma types. Full interpretation therefore requires consideration of clonality and other markers. | |||
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<span style="color:navy">'''Normal expression and function'''</span> | <span style="color:navy">'''Normal expression and function'''</span> | ||
CD5 | 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 expression is expressed at higher level on T cells than B cells, and expression is increased on activation. | ||
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<span style="color:navy">'''Diagnostic role'''</span> | <span style="color:navy">'''Diagnostic role'''</span> | ||
* | **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. | |||
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<span style="color:navy">'''Other relevant information:'''</span> | <span style="color:navy">'''Other relevant information:'''</span> | ||
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”. | |||
Revision as of 17:15, 30 April 2023
- Summary
- Although principally a T-cell antigen, the main diagnostic role of CD5 is in diagnosis of B cell disorders:
- For 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
- This marker is expressed by normal T cells and a subset of normal B cells, and is found with low frequently on other lymphoma types. Full interpretation therefore requires consideration of clonality and other markers.
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 expression 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