title: Diurnal variation of circulating human myeloid progenitor cells.
abstract: We investigated whether human circulating myeloid progenitor cells (CFU(c)) exhibit diurnal variation. Peripheral venous blood samples were drawn every 3 h from each of the nine healthy male volunteers. Blood mononuclear cells were harvested by the Ficoll-Hypaque method. CFU(c) content of blood was determined by the soft agar cloning assay. Human placental conditioned medium (HPCM) was used as colony stimulating factor. We found a 24 h cyclic variation of colonies/10(5) mononuclear cells plated with a maximum at 9 a.m. (P < 0.01). Analysis of the colonies by in situ staining indicated that this variation could be attributed almost entirely to colonies composed of eosinophilic cells (representative of CFU(eos)). Neutrophil/macrophage colonies (representative of CFU(G,M)) exhibited a trend toward a 9 a.m. maximum, but this variation was not statistically significant. We conclude that time of blood collection should be standardized in experiments measuring human peripheral blood CFU(c).
authors.affiliation: Laboratory of Clinical Biochemistry, Baltimore Cancer Research Program, DCT, NCI, NIH, 655 West Baltimore Street, Baltimore, MD 21201, USA.
authors.forename: D D
authors.initials: DD
authors.lastname: Ross
authors.forename: A
authors.initials: A
authors.lastname: Pollak
authors.forename: S A
authors.initials: SA
authors.lastname: Akman
authors.forename: N R
authors.initials: NR
authors.lastname: Bachur
mesh_terms: D002478:Cells, Cultured; D002940:Circadian Rhythm / Q000502:physiology*; D003114:Colony-Forming Units Assay; D006801:Humans; D008264:Macrophages / Q000166:cytology / Q000502:physiology*; D008297:Male; D023461:Myeloid Progenitor Cells / Q000166:cytology / Q000502:physiology*; D009504:Neutrophils / Q000166:cytology / Q000502:physiology*