Test2
From haematologyetc.co.uk
- CD3 is a reliable marker of T cell lineage that is primarily used to distinguish between T and B cells. The pattern of expression has diagnostic relevance.
Normal expression and function
CD3 is a multi-molecular complex that associates with the T cell receptor of mature T cells, and supports TCR expression and intracellular signalling in response to antigen. It is first expressed in the cytoplasm of pro-thymocytes before migrating to the T-cell surface during thymic maturation. CD3 expression is almost exclusive to mature T cells (there is weak expression of CD3 by some macrophages).
Diagnostic role
- T-ALL Expression is mainly cytoplasmic (cyCD3). Surface (sCD3) is usually absent in Early T-precursor T-ALL but is variably expressed in more mature T-ALL.
- Mature T cell neoplasms: sCD3 is expressed on T cell lymphoproliferative disorders. The level of CD3 expression is increased (compared to normal T cells) in T-PLL and T-LGL, and is decreased in Sézary syndrome and ATLL
- Natural Killer cell lymphoproliferative disorders: do not express a conventional TCR so CD3 is not expressed.
- Other B cells rarely express CD3, and aberrant expression in AML is rare (in contrast to other T cell markers such as CD2 or CD7).
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
B ALL
- Hi.png
Pro-T ALL
- Hi.png
Mature-T ALL
- Poss.png
AML *
- Rare.png
Haemato-gones
* May be seen in AML but consider bi-phenotypic if present
Expression by B-lymphoproliferative disorders
- Rare.png
CLL
- Rare.png
PLL
- Rare.png
MCL
- Poss.png
FL *
- Rare.png
HCL
- Rare.png
HCLv
- Rare.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
KEY
The indicated expression frequency, indicates the approximate frequency of occurrence in each particular disease type.
rare (<5%)
possible (5-20%)
likely (20-40%)
frequent (40-80%)
expected (>80%)
Where expression level is unusual or characteristic of a disorder this is indicated by text: