QUANTITATIVE CD34 ANALYSIS MAY BE USED TO GUIDE PERIPHERAL-BLOOD STEM-CELL HARVESTS

The duration of neutropenia and thrombocytopenia after high-dose chemo therapy has improved since the introduction of myeloid growth factors and peripheral blood progenitor cells (PBPC), yet there remains a subs et of patients who have delayed hematopoietic recovery, Currently, the re are no established, reliable parameters which may be used to guide stem cell harvests, We investigated the utility of measuring harvested CD34 positive cell populations by flow cytometry, From March 1990 to July 1993, 30 women with advanced breast cancer underwent therapy with high-dose cyclophosphamide and thiotepa and stem cell rescue, Patient s received either cyclophosphamide (CY) mobilized PBPC or CY/G-CSF mob ilized PBPC, The number of harvested CD34(+) cells and CFU-GM (colony forming units-granulocyte macrophage) were quantitated for each stem c ell product, There are complete CD34 data for 21 patients and complete CFU-GM data for 20 patients, There was a significantly delayed neutro phil recovery in those patients reinfused with <0.75 x 10(6) CD34(+) c ells/kg body weight (median days 22) compared with patients reinfused with >0.75 x 10(6)/kg (median days 12, P = 0.0004); a similar trend wa s seen with platelet recovery (median 135 days vs 18 days, respectivel y, P = 0.002), With neutrophil recovery, there was no improvement in t ime to engraftment with a larger number of reinfused CD34(+) cells, bu t there was a trend towards shortened platelet recovery when the numbe r of reinfused CD34(+) cells exceeded 2.0 x 10(6)/kg (median 15 days) compared with CD34(+) <2.0 x 10(6)/kg (median 75 days, P = 0.05), Thos e patients who had <0.75 x 10(6) CD34(+) cells had longer hospitalizat ions (P = 0.007) and greater platelet transfusion requirements (P = 0. 02), There was a significant positive correlation between CD34 and CFU -GM (r = 0.69, P<0.001, beta(1) = 0.148), The number of reinfused CD34 (+) cells correlates with hematopoietic recovery and may be used to gu ide the harvesting of peripheral blood stem cells, Further experience and reliability of the CD34 assay must be obtained, however, before un iversal recommendations can be made.