A SIMPLIFIED METHOD OF CD34(-BLOOD PROGENITOR-CELL TRANSPLANTATION AND CORRELATION WITH CLINICAL ENGRAFTMENT() CELL DETERMINATION FOR PERIPHERAL)

Enumeration of CD34(+) cells by flow cytometry is the recognized stand ard for quantitating progenitor cells for peripheral blood progenitor cell (PBPC) transplantation. Although many clinical studies have confi rmed that the time to neutrophil and platelet engraftment is inversely proportional to the number of CD34(+) cells infused, the minimum numb er of CD34(+) cells necessary to acheive rapid engraftment has not bee n satisfactorily determined. The lack of a standardized method for qua ntitation of CD34(+) cells by flow cytometry (FCM) is often cited as t he reason for this ambiguity. This report describes an FCM method for CD34(+) cell determination that is simple, highly reproducible, compar atively inexpensive, and validated by excellent correlation with clini cal engraftment. Pheresis samples are stained and fixed within 4 hours of collection. Two hundred fifty thousand events are acquired as list mode data using a forward scatter threshold. The discrete CD34(+) pop ulation is enumerated using a CD34-phycoerythrin FL2 vs. side scatter plot and Paint-A-Gate Pro software. The method was validated by excell ent statistical correlation with clinical engraftment. Using this meth od, we determined the number of CD34(+) progenitor cells necessary to achieve rapid engraftment to be 2x10(6)/kg.