title: Myelopoiesis following phorbol ester exposure in human long-term bone marrow cell culture.
abstract: Phorbol esters have two opposing effects on bone marrow granulocyte/macrophage colony forming cells (CFC-GM): they reduce the number of CFC-GM which respond to colony-stimulating activity (CSA), and they also induce the release of CSA from accessory marrow cells. We questioned whether the direct inhibitory effect of phorbol esters on CFC-GM was reversible and whether phorbol ester-treated accessory bone marrow cells could increase the in vitro recovery of cultured CFC-GM. Normal human bone marrow cells were exposed to phorbol-12,13-dibutyrate (PDB) for 5 days in liquid cultures. Total nucleated cell counts decreased in a dose-dependent fashion to 42 +/- 6% of control at 5 X 10(-8) M PDB, and CFC-GM decreased to 20 +/- 8% of control. The cultures were then washed to remove PDB and continued for up to 8 weeks. Total cell counts and CFC-GM/ml remained reduced in PDB-pretreated cultures compared to control. To determine whether this was a direct effect of PDB on nonadherent, proliferating cells or whether PDB acted indirectly by affecting adherent, accessory cells, nonadherent bone marrow cells from control and PDB-preincubated cultures were co-cultured for 8 weeks with either control or PDB-preincubated adherent bone marrow cells. Nonadherent cells preincubated with PDB had a similar growth pattern whether or not the co-cultured adherent cells had been preincubated with PDB. In contrast, nonadherent cells preincubated in control medium and co-cultured with PDB-preincubated adherent cells displayed increased numbers of nucleated cells, CFC-GM and adherent hematopoietic islands compared to control. This was associated with increased amounts of CSA present in the culture supernatants. Thus PDB causes an irreversible decrease in CFC-GM in long term marrow cultures but enhances the ability of adherent stromal cells to support normal CFC-GM growth in culture.
mesh_terms: D001853:Bone Marrow / Q000187:drug effects*; D002448:Cell Adhesion; D002478:Cells, Cultured; D003115:Colony-Stimulating Factors / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D006098:Granulocytes / Q000166:cytology; D006410:Hematopoiesis / Q000187:drug effects*; D006801:Humans; D008264:Macrophages / Q000166:cytology; D010703:Phorbol Esters / Q000494:pharmacology*; D010704:Phorbols / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D003115:Colony-Stimulating Factors; D010703:Phorbol Esters; D010704:Phorbols