Purification and partial characterization of a human hematopoietic precursor population

Abstract

This study reports the development of an assay, the Precolony-forming unit (CFU) assay, which detects human hematopoietic precursors. The Pre-CFU assay is based on the observation that precursors to CFU-granulocyte-macrophage (CFU-GM) that are undetectable in clonogenic assays differentiate into CFU-GM preferentially following treatment in suspension culture with recombinant human interleukin-1α (rhIL-1α) combined with rhlL-3. Using the Pre-CFU assay, hematopoietic precursors were detected in human bone marrow depleted of CFU-GM progenitors and differentiated hematopoietic elements via 4-hydroperoxycyclophosphamide treatment coupled with selection for CD34+ cells (4-HCresistant/CD34+ marrow). Additionally, the Pre-CFU assay detected recovery of hematopoiesis substantially earlier than the CFU-GM assay in primates following myeloablation with 5-flourouracil. The Pre-CFU assay was used to asses purification of a phenotypically defined hematopoietic precursor population, the lin CD34 population. The lin CD34 population lacks detectable surface markers for T-cell, B-cell, natural killer cell, and myeloid lineage, possesses the CD34 antigen, is devoid of CFU-GM progenitors, and yields PreCFU assay values comparable with 4-HCresistant/CD34+ marrow. Using a combination of phenotypic analysis and Pre-CFU assay analysis, the action of rhlL-1α plus rhlL-3 treatment on lin CD34+ cells was further characterized. The data indicate that rhlL-1α plus rhlL-3 treatment induces proliferation and differentiation of early hematopoietic precursors into progenitors and terminally differentiated cells, without inducing a significant expansion of the precursor population itself. © 1991 by The American Society of Hematology.