Aims:  The Plasma Cell Screening tube (PCST) from Cytognos is recommended as a screening tube for plasma cell dyscrasias and utilizes standardized Euroflow protocols.  For paraprotein investigation, our laboratory has replaced our standard 2- tube lymphoid and plasma cell analysis with this single tube assay. We report our first 12 months of experience using this method.

Method:

The PCST kit uses a Fix/Perm protocol and contains lyophilised premixed CD45/CD138/CD38/CD56/β2 Microglobulin/CD19/ CyIgKappa/CyIgLambda.  Samples were run on a FACSCanto II cytometer, and analysed with Infinicyt software. Validation was performed against our previous protocol which used an 8-colour B- lymphoid screening tube (CD45/CD3/CD5/CD10/CD19/CD20/sKappa/sLambda) and a plasma cell tube (CD19/CD38/CD45/CD138/CD56).

Results:

Validation was performed on 20 consecutive bone marrow samples with concordant results between methodologies. 200 clinical samples were analysed with the PCST between September 2015 and September 2016.   These included a range of normal/reactive samples , plasma cell dyscrasias, lymphoplasmacytoid and lymphoid neoplasms.  Normal/reactive plasma cells are readily distinguished from neoplastic counterparts where plasma cells are <1% of total nucleated cells.  For B-cell clonality, dim CD19 expression or where there is only a small malignant population amongst a large normal background, it is not as sensitive as our 8-colour B lymphoid screening tube.

Conclusion: The PCST single identifies plasma cells and discriminates between normal/reactive cells and their neoplastic counterparts.  In the majority of cases it will also identify monoclonal B- cell populations, but our 2 tube lymphoid screening panel remains our most sensitive screening panel for primary lymphoid neoplasms.