AUTOGRAFTING WITH BLOOD PROGENITOR CELLS - PREDICTIVE VALUE OF PREAPHERESIS BLOOD-CELL COUNTS ON PROGENITOR-CELL HARVEST AND CORRELATION OFTHE REINFUSED CELL DOSE WITH HEMATOPOIETIC RECONSTITUTION

One hundred and nine patients suffering from various malignancies unde rwent 285 apheresis procedures for PBPC collection. A median of two le ukaphereses (range: 2-5) resulted in median numbers of 4.6x10(8) MNC/k g, 14.1x10(4) CFU-GM/kg, and 6.0x10(6) CD34+ cells/kg. Preleukapheresi s peripheral blood CD34+ cells correlated significantly with collected CD34+ cells/kg (r=0.94; p<0.0001) and with CFU-GM/kg (r=0.52; p<0.000 1), A value >4x10(4) CD34+ cells/ml was highly predictive for a collec tion yield >2.5x10(6) CD34+ cells/kg harvested by a single leukapheres is. Sixty patients were evaluated for hematologic reconstitution and e ngrafted in a median time of 10 days for WBC >1.0x10(9)/l (range: 7-21 days), 10 days for ANC >0.5x10(9)/l (7-20) and 11 days for PLT >20x10 (9)/l (7-62). Reinfused CD34+ cells/kg correlated significantly with h ematologic engraftment (r=0.44-0.52 and p<0.006-0.001) as well as CFU- GM/kg (r=0.36-0.44 and p<0.007-0.001). A progenitor cell dose >2.5x10( 6) CD34+ cells/kg or >8.0x10(4) CFU-GM/kg led to a significantly faste r recovery for WBC, ANC, and PLT when compared with patients receiving <2.5 x 10(6) CD34+ cells/kg or <8.0x10(4) CFU-GM/kg. We conclude that rapid hematopoietic engraftment after high-dose therapy and PBPC rein fusion correlates well with a progenitor cell dose >2.5x10(6) CD34+ ce lls/kg or >8.0x10(4) CFU-GM/kg, and that above a preleukapheresis thre shold of 4x10(4) CD34+ cells/ml a PBPC autograft containing >2.5x10(6) CD34+ cells/kg can be collected by a single leukapheresis. We suggest that patients recovering from myelosuppression should be monitored fo r CD34+ cells in serial blood samples to determine the course of circu lating hematopoietic progenitor cells. This issue will help to define the optimal time point to start apheresis and to predict a PBPC autogr aft harvested by a single leukapheresis, which will lead to rapid and stable hematopoietic reconstitution following transplantation.