Flow cytometry immunophenotyping and minimal residual disease evaluation in multiple myeloma

Abstract

Objective To investigate the characteristics of immunophenotyping and clinical significance of MRD analysis in MM patients. Methods Multi-parameter flow cytometry was applied to analyze the immunophenotyping of malignant plasma cells from 172 MM patients, and normal plasma cells from 16 healthy individuals. MRD was analyzed in 32 MM patients with remission. Meanwhile, the effects of MRD status on the disease relapse and patient disease free survival ( DFS ) time was evaluated by following up patients. Results The immunophenotyping of normal plasma cells were CD38, CD138, CD19 and CD45 positive, while the predominant phenotype of MM cells were CD+38( 100.0% ), CD+138( 100.0% ), CD-19 ( 167/172, 97. 1% ), CD+56( 152/172, 88.4% ) and CD-45( 166/172, 96. 5% ). The characteristic markers for MM cells were CD+38, CD-138, CD-19, CD-45 and CD+56. MRD analysis revealed that, among 32 MM patients with remission, 14 patients were MRD negative and 18 patients were MRD positive. During follow-up of 2 to 16 months, the relapse rate in MRD negative patients was significantly lower ( 4/14, 28.6% ) than that of MRD positive patients ( 13/18, 72. 2% ;χ2 =6. 03, P ＜0. 05 ). Furthermore, the DFS time was significantly longer in MRD negative patients[ 16. 23( 10. 37-21.62 )months ] than that of the MRD positive patients [ 10. 07( 3. 79-16. 20 )months,χ2 =7. 53,P ＜0. 05 ]. Conclusions CD+38, CD+138, CD-19, CD-45 and CD+56 are the characteristic markers of MM cells compared to those of the normal plasma cells. MRD analysis is a valuable prognostic factor for MM patients. Key words: Multiple myeloma; Immunophenotyping; Neoplasm,residual; Flow cytometry