CD34-positive cell proportions in peripheral blood correlate with colony-forming capacity

Blood samples were examined from 25 children with malignancies during hematopoietic recovery following chemotherapy-induced aplasia and from 9 children undergoing tonsillectomy. The proportion of CD34-positive peripheral blood mononuclear cells (PBMNC) evaluated by flow cytometry was compared with the number of colonies (granulocyte-macrophage colony-forming units, CFU-GM; mixed-lineage colony-forming units, CFU-GEMM; and erythroid burst-forming units, BFU-E) grown in methylcellulose medium within 2 weeks. A mean of 1387 myeloid colonies (495-4480) per 10(5) PBMNC seeded developed from 13 samples with detectable CD34 populations (between 0.9% and 5.6%), whereas only 152 (9-386, p = 0.002) and 65 (12-137, p = 0.005) colonies were formed from 12 patient and from 9 control samples in which the percentage of CD34-positive cells was too low for analysis. Linear regression analysis revealed that CD34 positivity correlates with colony-forming capacity (p = 0.0008, r = 0.782). Flow cytometric evaluation of the CD34 proportions can thus predict the in vitro colony-forming capacity of peripheral blood prior to leukapheresis.