engleski

Diagnostic utility of multiparameter flow cytometric immunophenotyping in multiple myeloma

Background-aim. Flow cytometric immunophenotyping has been widely used to identify neoplastic plasma cell populations (PCs) in patients with multiple myeloma (MM). Markers that have been associated with informative aberrant antigen expression profiles for MM according to European Myeloma Network (EMN) guidelines are: CD19, CD56, CD45, CD38, CD27, CD20, CD28, CD33, CD117 and to a less extent also CD81 and CD200. In combination with cytoplasmic immunoglobulin (cytIg) KAPPA and LAMBDA light chain staining, they contribute to establish the clonal nature of a population of suspicious PCs. The aim of this study was to evaluate the diagnostic utility of flow cytometric imunophenotyping (FCI) for MM analysis. Methods. In 2018 FCI was done on bone marrow specimen from 40 patients, 18 females (49–83 years) and 22 males (52–85 years), characterized as newly diagnosed (13), stationary MM (11) or relapsed MM (16), respectively. Multiparametric flow cytometric immunophenotyping was performed using monoclonal antibodies against CD138, CD38, CD45, CD56, CD19, CD20, CD33, CD117, CD200, CD27 and CD28, cytKAPPA, cytLAMBDA following the procedure for intracytoplasmatic determination. Backbone markers CD38, CD45 and CD138 were included in all tests. All measurements were performed on a flow cytometer Navios, Beckman-Coulter, in 10 color analysis. Gating procedure was based on CD38 vs. CD138 antigen expression. Results. PCs population accounted 0.4–64% of the total nucleated cell count by flowcytometry. The abnormal antigen expression pattern as defined by EMN in 40 MM cases, was found for: CD45 (75%), CD56 (82.5), CD19 (90%), CD20 (8.1%), CD33 (45%), CD117 (60%), CD200 (82.1%), CD27 (57.5%) and CD28 (37.5%), respectively. Light chain restriction was demonstrated in all of them, with either KAPPA (30) or LAMBDA (10) clonal expression. Conclusions. Although CD19, CD56 and CD200 represented as the most valuable antigens for identifying neoplastic population in patients with MM, they can't stand alone to distinguish normal/reactive vs. tumor cells. The immunophenotyping panel proposed by EMN is powerful for distinguishing neoplastic from reactive plasma cells in clinical practice. Standardization in processing, analysis and reporting increases objectivity of FCI findings in cases when MM is suspected.

flow cytometric immunophenotyping ; multiple myeloma

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