外周血CD_(34)~+细胞检测对外周血干细胞采集结果及时机选择的意义

 目的　研究外周血CD+34 细胞数对采集结果的意义，并探索可用于临床指导外周干细胞采集时机选择的参考阈值。方法　2007年1月至2009年12月共57例次自体造血干细胞移植动员采集患者，以环磷酰胺（CTX）化疗+粒细胞集落刺激因子（G-CSF）（5～10 μg／kg）动员，COBE分离仪（Spectra Version 6）行外周血造血干细胞采集，应用流式细胞术监测外周血中CD+34 细胞绝对计数。结果　采集产品单个核细胞（MNC）中位数4.6×108／kg（0.3×108／kg～10.5×108／kg），CD+34 细胞中位数2.4×106／kg（0.16×106／kg～34.9×106／kg），外周血CD+34 细胞数是产品MNC和CD+34 细胞总量唯一相关指标，外周血白细胞（WBC）与采集产品MNC和CD+34 细胞数无关。进一步分析提示外周血CD+34 计数≥15／μl，单次采集效率提高，CD+34 细胞采集量达1×106／kg和2×106／kg比例为81 %和60 %，采集产品MNC和CD+34 总数明显提高。提示外周血CD+34 细胞数15／μl可作为启动采集。ROC分析发现外周血CD+34 细胞 25（26.5～28.6）／μl，单次采集足量CD+34 细胞概率最大。结论　外周血CD+34 细胞计数是外周血自体干细胞采集重要的相关指标，CD+34 细胞 15／μl可作为采集时机选择的阈值。

Significance of peripheral CD_(34)~+ cell count on the harvest of mobilized peripheral hematopoietic stem cells

Objective Autologous hematopoietic stem cell transplantation (Auto-HSCT) has been widely used in hematological malignancies.To mobilize and harvest sufficient number of peripheral CD_(34)~+ cells is one of key issues for auto-HSCT. Peripheral CD_(34)~+ cell numeration has been used as an indicator for apheresis while we mostly rely on the peripheral WBC or MNC count. In this study, we try to evaluate the association of peripheral CD_(34)~+ count to the CD_(34)~+ cells number in the apheresis product and to find out a potential threshold. Methods From Jan 2007 to Dec 2009, a total of 57 apherosis for auto-HSCT were analysed. All patients were mobilized by cyclophophamide (CTX) plus G-CSF(5-10μg/kg) regimen. The apheresis were performed with COBE SPECTRA VERSION 6 and CD_(34)~+ count of both peripheral and apheresis products were analysed by flow cytometry. Results The median number of MNC in apheresis products was 4.6(0.3-10.5)×10~8/kg with median CD_(34)~+ cells at 2.4(0.16-34.9)×10~6/kg. The peripheral CD_(34)~+ count was the only parameter associated with the MNC and CD_(34)~+ cell numbers in the apheresis products while the WBC number was irrelevant to the results of apheresis. Our data showed that when the peripheral CD_(34)~+ count reach 15/μl, the efficacy of a single apheresis significantly improved with 81 % and 60 % reached 1 and 2×10~6 CD_(34)~+ cells/kg respectively and the total number of MNC and CD_(34)~+ cells were significantly superior to apheresis with peripheral CD_(34)~+ cells <15/μl, thus indicated that CD_(34)~+ ≥15 /μl can be used as the threshold for apheresis. Furthermore, the ROC analysis demonstrated that CD_(34)~+ cells ≥25(26.5-28.6) /μl is the best indicator level for a successful single apheresis. Conclusion Our study clearly showed that peripheral CD_(34)~+ cell count is a key indicator of apherosis. CD_(34)~+ cells at 15/μl can be used as the threshold to start apheresis in the clinical setting.