Effects of storage time of bone marrow specimens on the detection results of plasma cells immunophenotyping by flow cytometry / 白血病·淋巴瘤

ABSTRACT

Objective To explore the effects of different storage time of bone marrow specimens on the expressions of different antigens in normal plasma cells (nPC) and clone plasma cells (cPC) by flow cytometry. Methods The bone marrow samples of 12 patients with multiple myeloma (MM) who were treated in Beijing Chaoyang Hospital from September 2017 to January 2018 were selected as MM group. The minimum residual disease (MRD) level in MM group was 10-3-10-2. The bone marrow samples of 12 patients without plasma cell diseases were used as control group. Bone marrow samples were anticoagulated with ethylenediaminetetraacetic acid dipotassium (EDTA-K2) and stored at 2-8 °C. The fluorescent antibodies CD56, CD138, CD45, CD38, CD117, CD81 and cκ, cλ, CD45, CD38, CD19, CD27 were labeled at 0, 24, 48 and 72 h, respectively. The average fluorescence intensity (MFI) of the above 10 antigens expressed in nPC and cPC was analyzed by Diva software. The proportion and absolute count of nPC in control group and cPC in MM group were analyzed. Results In control group, when stored for 24 h, compared with 0 h, the difference of MFI of antigens in nPC was not statistically significant (P ＞ 0.05). When stored for 48 h, compared with 0 h, the MFI of CD38, CD138, CD27, cκ and cλ in nPC decreased, and the differences were statistically significant (28 943±6 591 vs. 23 569±7 587, P＝ 0.018; 1 412±399 vs. 817±223, P＝ 0.014;12 855±3 734 vs. 9 210±3 660, P＝ 0.005; 26 712±9 025 vs. 17 247±5 078, P＝ 0.026; 17 707±8 633 vs. 8 307±3 158, P ＝ 0.049); the MFI of CD45 increased, and the difference was statistically significant (7 694± 2 525 vs. 9 184±1 332, P ＝ 0.037). When stored for 72 h, compared with 0 h, the MFI of cκ and cλ increased, but the differences were not statistically significant (both P ＞ 0.05). In MM group, when stored for 24 h, compared with 0 h, the difference in MFI of antigens in cPC was not statistically significant (P＞ 0.05). When stored for 48 h, compared with 0 h, the MFI of CD38, CD138, CD81, cκ and cλ decreased, and the differences were statistically significant (16 664±11 744 vs. 10 130±10 026, P＝ 0.003; 2 041±1 145 vs. 1 371±696, P＝ 0.047; 2 679±784 vs. 1 524±1 153, P＝ 0.025; 29 102±18 138 vs. 18 372±10 327, P＝0.038; 16 314±12 728 vs. 9 752±6 271, P＝0.034). When stored for 72 h, compared with 0 h, the MFI of cκ and cλ increased, but the differences were not statistically significant (both P＞ 0.05). The absolute count of nPC and cPC gradually decreased with the prolongation of the storage time, and the difference was statistically significant (both P<0.05) when stored for 0 h and 24 h. There was no significant difference in the percentage of nPC and cPC among different storage time (all P ＞ 0.05). Conclusion Different storage time of bone marrow samples has effects on the MFI of antigens and absolute count of nPC and cPC, and the detection should be completed within 48 h.