title: Regulation of human eosinophil viability, density, and function by granulocyte/macrophage colony-stimulating factor in the presence of 3T3 fibroblasts.
abstract: Normodense human peripheral blood eosinophils were isolated under sterile conditions from the 22/23 and 23/24% interfaces and the cell pellet of metrizamide gradients. After culture for 7 d in RPMI media in the presence of 50 pM biosynthetic (recombinant) human granulocyte/macrophage colony-stimulating factor (rH GM-CSF), 43 +/- 7% (mean +/- SEM, n = 8) of the cells were viable; in the absence of rH GM-CSF, no eosinophils survived. The rH GM-CSF-mediated viability was concentration dependent; increased survival began at a concentration of 1 pM, a 50% maximal response was attained at approximately 3 pM, and a maximal effect was reached at concentrations of greater than or equal to 10 pM rH GM-CSF. In the presence of rH GM-CSF and mouse 3T3 fibroblasts, 67 +/- 6% (mean +/- SEM, n = 8) of the eosinophils survived for 7 d. In a comparative analysis, there was no difference in eosinophil viability after 7 and 14 d (n = 3) in the presence of 50 pM GM-CSF and fibroblasts. Culture with fibroblasts alone did not support eosinophil survival. The addition of fibroblast-conditioned media to rH GM-CSF did not further improve eosinophil viability, indicating a primary role for GM-CSF in supporting these eosinophil cell suspensions ex vivo and a supplementary role for 3T3 fibroblasts. Eosinophils cultured for 7 d localized on density gradient sedimentation at the medium/18, 18/20, and 20/21 interfaces of metrizamide gradients, indicating a change to the hypodense phenotype from their original normodense condition. In addition, the cultured eosinophils generated approximately 2.5-fold more LTC4 than freshly isolated cells when stimulated with the calcium ionophore A23187 and manifested sevenfold greater antibody-dependent killing of S. mansoni larvae than the freshly isolated, normodense cells from the same donor. Thus we demonstrate the rH GM-CSF dependent conversion in vitro of normodense human eosinophils to hypodense cells possessing the augmented biochemical and biological properties characteristic of the hypodense eosinophils associated with a variety of hypereosinophilic syndromes. In addition, these studies provide a culture model of at least 14 d suitable for the further characterization of hypodense eosinophils.
mesh_terms: D000818:Animals; D000920:Antibody-Dependent Cell Cytotoxicity; D000001:Calcimycin / Q000494:pharmacology; D002452:Cell Count; D002470:Cell Survival; D002478:Cells, Cultured; D002499:Centrifugation, Density Gradient; D004804:Eosinophils / Q000166:cytology / Q000187:drug effects / Q000276:immunology*; D005347:Fibroblasts / Q000502:physiology*; D006801:Humans; D007377:Interleukin-3 / Q000502:physiology*; D051379:Mice; D009504:Neutrophils / Q000502:physiology; D011994:Recombinant Proteins / Q000502:physiology; D013189:SRS-A / Q000096:biosynthesis; D012550:Schistosoma mansoni / Q000276:immunology; D013997:Time Factors
chemical_list: D007377:Interleukin-3; D011994:Recombinant Proteins; D013189:SRS-A; D000001:Calcimycin