[Comparison and analysis of minimal residual disease in multiple myeloma patients detected by 4-color and 8-color fluorescence antibody panels].

Objective: To explore and compare 4-color and 8-color fluorescence antibody panels for detecting minimal residual disease of multiple myeloma patients after therapy. Methods: One 8-color antibody panel was built including CD38 and CD138 for the identification of plasma cells (PCs) , membrane antigen CD45, CD19, CD56 and CD117, cytoplasmic Kappa (cκ) and Lambda (cλ) light chain antigen. Six tubes of 4-color panels were built, among them, membrane antigen CD45/CD19, CD56/CD117, CD19/CD56 and light chains were analyzed combined by CD38/CD138 for PCs gate in the tubes M1-3 and tube C-(κ/λ), respectively; CD19 or CD45 and cκ/cλ light chains were detected in the tube MC1-(C)D38 for CD38/SSC identified PCs gate and tube MC2-(CD138) for CD138/SSC identified PCs gate separately. Twenty normal volunteer bone marrows and seventy-three specimens from multiple myeloma patients after complete remission were measured and analyzed. Results: MRD positive samples were discriminated in 82.19% of the specimen evaluated through either abnormal plasma cells (aPCs) or clonal plasma cells (cPCs) by 8-color antibody panel. Among of them, consistency was 89.04%. The median percentage of cPCs was 0.105%. The lowest sensitivity of experiment was 0.004%. Percentage of PCs identified by CD38/ SSC gate was higher than that by CD38/CD138 ( P <0.001) and CD138/SSC gate ( P =0.001) apparently. The lowest MRD positive rate was found in tube C (65.75%) , which lower than 8-color panel obviously ( P =0.024) . The percentages of aPCs measured by tube M2-(56/117) were significantly lower than other tubes ( P =0.014) . MRD positive rate determined by cPCs was higher than that by aPCs both in the tube MC1-(C)D38 and tube MC2-(CD138), whose concordance rate were 68.49% and 79.45%, respectively. Compared with 8-color panel, tube MC2-(CD138) the best choice among six tubes of 4-color panels, which has the best sensitivity, accuracy and negative predicted value, higher positive predicted value and specificity. Tube M1-(45/19) was the second choice. Conclusions: CD38/CD138 are the best markers for gating PCs. Membrane antigen and cκ/cλ detected simultaneously is a better method for MM MRD detection and 8-color antibody panel is an ideal approach. Two tubes of 4-color antibody combination, M1-(45/19) and MC2-(CD138) are recommended in the 4-color panels.