Flow Cytometry:T-Lymphoid lineage assignment
From haematologyetc.co.uk
| Assignment of T-lymphoid lineage | |
|---|---|
| For T-lymphoid lineage assignment the key lineage-marker is CD3. Provided that this marker meets the intensity criteria then it is T-lineage defining in MPAL. This expression can be determined either by CD3 detection by flow cytometry OR by immunocytochemistry on trephine. | |
| Either CD3 surface or cytoplasm (strong) Or CD3 by immunocytochemistry (strong) | To meet the definition of "strong" the expression intensity must exceed that of 50% of normal T lymphocytes |
Notes on interpretation of T-lineage in MPAL
Expression of CD3 is required to assign T lineage in MPAL. Generally, other T-associated antigens will also be expressed:.CD7, and in the majority of cases. CD2, CD4, CD5, and CD8. Consider also that a proportion of early T precursor lymphoblastic leukaemia/lymphoma (ETP-ALL) may be difficult to distinguish from MPAL-T/M. Using an appropriate threshold for MPO positivity may be helpful and a threshold of >10% for myeloperoxidase positivity is broadly advised by WHO in this context.