LARGE-SCALE ENRICHMENT OF MOBILIZED CD34(-BLOOD HEMATOPOIETIC PROGENITORS BY REMOVAL OF NYLON WOOL ADHERENT MATURE CELLS() PERIPHERAL)

With the aim of facilitating the ex vivo manipulation of peripheral bl ood hematopoietic progenitors (CPCs = circulating progenitor cells) co llected by leukapheresis, we removed polymorphonuclear cells and monoc ytes that naturally adhere to nylon wool fibers. Leukapheresed cells h arvested at the time of hematopoietic recovery after cancer therapy wi th high-dose cyclophosphamide plus hematopoietic growth factors were i ncubated with nylon wool fibers for Ih at 37 degrees C. Evaluation of the cells non-adherent to the nylon wool in all experiments (n = 14) s howed that the median recovery of nucleated cells and CPCs detected as CD34(+) cells, CFU-GM and BFU-E was 16.4% (range 4.8%-34.0%), 60.0% ( range 30.8-80.8%), 60.9% (range 33.4-74.5%) and 65.5% (range 30.8-69.2 %), respectively. Therefore exposure to the nylon wool determined a se lective removal of mature cells and a complementary enrichment of CPCs . The wide range of results depended on the significantly different ce ll compositions of the unmanipulated leukaphereses. The latter from pa tients receiving rhG-CSF (n = 10) comprised a median of 88.5% (range 7 7.8-93.8%) and 11.5% (range 6.2-22.2%) polymorphonuclear and mononucle ar cells, respectively. In contrast, leukaphereses from patients recei ving rhGM-CSF or PIXY321 (n = 4) comprised a median of 71.1% (range 55 .4-85.0%) and 28.9% (range 15.0-44.6%) polymorphonuclear and mononucle ar cells, respectively. Accordingly, the fold-enrichment and recovery of hematopoietic progenitor cells was significantly higher for leukaph eresed cells from patients receiving rhG-CSF (fold-enrichment = median 4.8, range 3.5-14.6; recovery = median 63.0%, range 57.9-80.9%) than from patients receiving rhGM-CSF or PIXY321 (fold-enrichment = median 1.7, range 1.4-2.0; recovery = median 34.4%, range 30.8-47.1%). Nylon wool adherence represents a rapid and efficient method for the enrichm ent of CPCs for clinical use.