LIMITING-DILUTION ANALYSIS OF THE EFFECTS OF COLONY-STIMULATING FACTORS, PHYTOHEMAGGLUTININ, AND HYDROCORTISONE ON HEMATOPOIETIC PROGENITOR-CELL GROWTH

  • 1 November 1987
    • journal article
    • research article
    • Vol. 70  (5) , 1611-1618
Abstract
The effects of colony-stimulating factors (CSFs), phytohemagglutinin (PHA), and hydrocortisone on the growth of human bone marrow hematopoietic progenitor cells (granulocyte-macrophage; GM) were analyzed in a limiting-dilution assay (LDA). Both low-density bone marrow cells separated by discontinuous Percoll gradients and a T cell-depleted and progenitor-enriched cell fraction obtained by the combination of counterflow elutriation centrifugation and Percoll gradients were examined in LDA. GCT (monocytoid cell line-conditioned medium containing GM-CSF), human placenta-conditioned medium, bladder carcinoma cell line 5637-conditioned medium (containing GM- and G-CSF), and recombinant CSF (G-CSF) directly induced proliferation of progenitors with single-hit kinetics. In some instances, however, PHA-stimulated lymphocyte-conditioned medium (containing G- and GM-CSF) showed deviation from single-hit kinetics, which demonstrated the presence of factor(s) suppressive to progenitor growth. In a T-cell-depleted, progenitor-enriched fraction, PHA alone was found to suppress progenitor growth at a level as low as 100 ng/mL. The addition of hydrocortisone (10-6 mol/L) increased the progenitor frequency but suppressed progenitor growth at 10-4 mol/L. LDA appears to be a valuable method for exploring mechanisms of factors regulating hematopoietic cell growth.

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