Evaluation of prognostic markers in plasma cell dyscrasias
Date
2017
Authors
Havyarimana, Sandra
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Abstract
Introduction:
Plasma cell dyscrasias (PCDs) are a heterogeneous group of diseases in which there is expansion of clonal plasma cells which may produce monoclonal immunoglobulins. CD200 is a membrane glycoprotein of the type I immunoglobulin superfamily transmembrane glycoprotein. It is postulated that CD200 is expressed by the plasma cells in a significant number of cases of multiple myeloma (MM), but normal plasma cells do not express it. It may thus assist in confirming clonality of plasma cells in PCDs.
Aims:
To evaluate CD200 expression as a potential diagnostic and prognostic marker in plasma cell dyscrasias and to compare the results with other known prognostic factors.
Methods:
CD200 expression was evaluated by immunophenotypic analysis on normal, reactive and clonal plasma cells and expressed as a mean fluorescent intensity (MFI) value. Cut-off for positive CD200 was established. A negative population was established using different methodologies to exclude reactive plasma cells. CD200 was then compared with diagnostic and prognostic markers currently in use in our laboratory.
Results:
An MFI of ≥ 30 was the cut-off for CD200 positivity. CD200 was expressed by 76.5% of PCDs cases. CD200 did not predict anaemia, hypercalcaemia or renal dysfuction which are biochemical criteria for the diagnosis of multiple myeloma. CD200 expression did not correlate with traditional prognostic markers such as beta 2 microglobulin (β2M), lactate dehydrogenase (LDH) or genetic abnormalities (by fluorescence in situ hybridization analysis). Cases with
plasma cell CD200 expression had a higher monoclonal band level compared to those without CD200 expression.
Conclusion:
CD200 is a useful tool to evaluate plasma cell clonality; however in our settings where there is a high prevalence of infectious diseases, particularly HIV infection, CD200 might yield false positive results most likely because of small oligoclones of reactive plasma cells. CD200 as a prognostic tool in PCDs could not be confirmed in this small study.
Description
A research report submitted to the Faculty of Health Sciences,
University of the Witwatersrand, Johannesburg,
in partial fulfilment of the requirements for the degree of
Master of Medicine in the Branch of Pathology (Haematology). Johannesburg, 2017.