The absolute number of circulating CD34+ cells as the best predictor of peripheral hematopoietic stem cell yield

Many controversies still exist about the timing of leukapheresis procedures for PBSC transplantation. Thirty-nine patients were followed daily by monitoring the absolute PB WBC count and CD34(+) cell enumeration prior to apheresis, These determinations were compared with the apheresis cell content (nucleated cells and CD34(+) cells yield). There was a highly significant correlation between PB CD34(+) cells and apheresis CD34(+) cell yield (r = 0.921, p < 0.001). A small but significant correlation was found between the PB WBC count and the apheresis nucleated cell content (r = 0.383, p < 0.001), but no correlation was found between PB WBC count and apheresis CD34+ cell yield (r = -0.065, p = 0.460), A target value of 20 x 10(6) CD34(+) cells/L was determined to be the most reliable predictor to collect at least 1.0 x 10(6) CD34(+) cells/kg in a single apheresis. Of the 39 patients, 20 could be followed after transplantation, and a good correlation was found for total number of CD34(+) cells reinfused and platelet and neutrophil engraftment, No correlation was found for nucleated cells infused and engraftment, CD34(+) cell determination is a better predictor than WBC count for timing leukapheresis and is thus recommended for monitoring the quality of the product.