异基因外周血干细胞移植后淋巴细胞和粒细胞嵌合体的动态改变

目的：探讨异基因外周血干细胞移植(allo-PBSCT)后T细胞、粒细胞嵌合体的动态改变及临床价值。方法：将多重PCR扩增短串联重复序列(STR—PCR)的法医试剂进行条件优化，间隔短时间抽取9例恶性血液病患者(5例清髓性PBSCT，4例非清髓性PBSCT)的外周血样，STR—PCR定量分析T细胞和粒细胞的嵌合体，并观察其对移植后应用免疫抑制剂的指导作用。结果：STR—PCR定量分析嵌合体的敏感性为5％，并具高度可重复性。清髓性PBSCT后10d( 10d)，5／5例患者的粒细胞迅速演变为完全供者嵌合体(CDC)， 14d，4，／5例患者的T细胞获得CDC。非清髓性PBSCT， 7～ 14d，供者T细胞信号的植入速度快于粒细胞；随后，供者粒细胞的比例突然增加，并迅速获得CDC，T细胞的植入却渐缓慢，最后，T细胞取得CDC的时间迟于粒细胞。依据供者T细胞信号的植入程度，及时调整非清髓性PBSCT后环孢素A(CsA)的用量，移植早期T细胞即获CDC，随访2～16个月，T细胞和粒细胞均呈稳定的供者植入状态。结论：供者T细胞的完全植入迟于粒细胞．动态监测T细胞嵌合体，可能有助于免疫抑制剂的调整。

Serial and quantitative analysis of lymphoid and myeloid chimerism after allogeneic peripheral blood stem cell transplantation

Objective:To explore the sequential change of chimerism in lymphoid and myeloid lineages after allogeneic peripheral blood stem cell transplantation (PBSCT).Method:A commercial multiplex short tandem repeat (STR) assay with fluorescence-based detection for forensic purposes was optimized. All blood samples were taken from 9 patients with hematologic malignancies at very short time intervals following ablative or nonablative PBSCT. The quantitative determination of chimerism in pure populations of T cells and neutrophils was performed using STR-PCR. The role of lineage-specific chimerism in directing immunosuppressive agents was also studied.Result:A sensitivity threshold was set at 5%, and reproducible results were obtained using optimized STR-PCR. By 10 days after ablative allo- PBSCT(day+10), the proportion of donor signals within myeloid cells attained complete donor chimerism (CDC) promptly in all five patients. By day +14, T-cells also gained CDC in 4/5 cases. By day 7 or 14 days after nonablative PBSCT, the proportion of donor STR signals within T cells was higher than that of myeloid cells. Thereafter, the proportion of donor signals within myeloid cells increased sharply to attain CDC, T cell engraftment became relatively slow. Ultimately, CDC in T cells lagged behind CDC in myeloid cells. Depending on the degree of donor signals in T cells, the dose of cyclosporine(CsA) was adjusted after nonablative PBSCT. CDC in T cells was gained in the early post-transplant period. Furthermore, stable T cell and myeloid cell engraftment was achieved following up 2 to 16 months.Conclusion:Complete donor T cell engraftment may lag behind donor myeloid engraftment. Sequential monitoring of T cell chimerism may be used to design individual patient immunosuppressive protocols.