New evaluations of circulating granulocyte and macrophage stem cells in healthy adults using conditioned media and recombinant human growth factors.

ABSTRACT

Peripheral human blood contains granulo-monocyte (CFU-GM) and eosinophil (CFU-Eo) progenitors. In vitro, the number of colony forming units is thought to range from 0.1-14 per 2 x 10(5) plated cells. We show that the number of CFU-GM, Eo depends on culture methods. By modifying the usual assay method (using human umbilical cord plasma and the association of 2 stimulating conditioned media activated lymphocyte conditioned medium and bone marrow fibroblast conditioned medium), we found different circulating CFU-GM, Eo numbers. The mean number of circulating CFU-GM, Eo in 107 healthy adults was 22.4 per 2 x 10(5) plated cells (range 1-84). There was a slight difference between males (mean number 23.6) and females (mean number 20.4). The mean number of CFU-GM, Eo harvested on Percoll gradient was 123/ml of peripheral blood (range 7-513). These results are far over those commonly reported in literature. This suggests that these latter results were probably underestimated. The use of recombinant human interleukin 3 and recombinant human GM (granulocyte-monocyte) colony-stimulating factors shows that CFU-GM, Eo numbers are found to be comparatively increased compared to that obtained with our modified method (using rhIL-3 alone), or that the size of those colonies is notably increased (using rhIL-3 + rhGM-CSF).