Abstract:

Objective To investigate the effect of different preservation methods on the stability of samples in external quality assessment （EQA）of paroxysmal nocturnal hemoglobinuria（PNH）by flow cytometry，and to lay the foundation for establishing an EQA system for PNH flow cytometry determination. Methods Totally，9 PNH positive fresh ethylenediaminetetracetic acid anticoagulated samples were collected. For each sample，the sample was mixed and then classified into 4 parts. The 3 parts of them were treated with 3 different cell preservation solutions，domestic company's cell preservation solution（Group A），foreign company's cell preservation solution（Group B）and acid-citrate-dextrose（ACD）cell preservation solution （Group C）. The remaining 1 part was used as control without adding cell preservation solution （Group D）. After the samples were treated，they were thoroughly mixed and divided into 5 parts and placed at 2-6℃. The sample stability under different preservation methods for 1，3，5，7 and 14 d was determined by standard flow cytometry recommended by the Clinical and Laboratory Standards Institute（CLSI） H52-A2. Results Compared with that at 2-6℃ for 1 d，the red blood cell PNH clone ratio exhibited a decreasing trend in Group A，B and D at 3，5，7 and 14 d（P<0.05），while Group C showed no statistical significance（P>0.05）. The white blood cell PNH clone ratio remained stable in Group B and C. There was statistical significance between 7，14 d and 1 d for Group A and D（P<0.05），and there was no statistical significance for Group A and D at 3 and 5 d as well as for Group B and C at 3，5，7 and 14 d compared to 1 d （P>0.05）. Conclusions In PNH determination，whether it is red blood cell PNH clone or white blood cell PNH clone，the samples with ACD preservation can meet the requirement of EQA sample stability within 14 d，ensuring the sample stability to the maximum extent possible.

Key words: Paroxysmal nocturnal hemoglobinuria, External quality assessment, Sample, Stability