From the Guidelines
Flow cytometry is the recommended study for patients with monoclonal gammopathy to characterize the abnormal cell population. This test analyzes cells from blood, bone marrow, or other tissues by labeling them with fluorescent antibodies that bind to specific cell surface markers. For monoclonal gammopathy evaluation, flow cytometry typically includes markers to identify plasma cells (CD38, CD138) and distinguish between normal and abnormal plasma cells (CD19, CD45, CD56, CD117) 1. The test requires a fresh sample (typically bone marrow aspirate or peripheral blood) that must be processed within 24-48 hours.
Key Points to Consider
- Flow cytometry helps determine if the plasma cell population is clonal (all derived from a single abnormal cell) and provides information about the percentage of abnormal plasma cells present.
- This information is crucial for distinguishing between monoclonal gammopathy of undetermined significance (MGUS), smoldering multiple myeloma, and active multiple myeloma, which guides treatment decisions.
- Flow cytometry results should be interpreted alongside other tests including serum protein electrophoresis, immunofixation, free light chain assay, and bone marrow biopsy findings for a comprehensive evaluation 1.
Important Markers
- CD38 and CD138 are used to identify plasma cells.
- CD19, CD45, CD56, and CD117 are used to distinguish between normal and abnormal plasma cells.
Recent Recommendations
- The European Myeloma Network recommends the use of flow cytometry for the diagnosis and monitoring of monoclonal gammopathies 1.
- A study published in 2018 found that flow cytometry can help identify patients with solitary plasmacytoma who are at high risk of progression to multiple myeloma 1.
- Another study published in 2010 found that flow cytometry can help predict the outcome of patients with smoldering multiple myeloma 1.
From the Research
Flow Study for Monoclonal Gammopathy
The flow study for a patient with monoclonal gammopathy involves the use of multiparametric flow cytometry to analyze circulating plasma cells in peripheral blood. This method allows for the simple and exact enumeration of circulating plasma cells, even in low quantities 2.
Key Components of Flow Study
- The phenotype profile and confirmation of clonality regarding bone marrow clonal counterparts should be verified 2.
- The analysis of plasma cells' phenotypic profile could clarify their future behavior 2.
- Flow cytometric aberrancies in plasma cell myeloma and MGUS can be correlated with laboratory parameters, such as CD19, CD27, CD28, CD56, and CD117 3.
Detection of Clonal Plasma Cells
- Multiparametric flow cytometry is a sensitive method for detecting circulating plasma cells 2.
- The use of polyclonal antibodies over monoclonal antibodies is preferred for the detection of intracellular immunoglobulin light chains 4.
- The free light-chain ratio can be predictive of clonal plasma cell presence and has prognostic implications 5.
Clinical Relevance
- The flow cytometry diagnostic threshold can be determined and implemented in plasma cell leukemia suspicious cases as well as in prognostication of monoclonal gammopathies patients 2.
- The standardization of analyses is the main goal, and a standardized approach can lead to more accurate identification of individuals at increased risk of developing symptomatic PC disorders 5.