IL-5-dependent conversion of normodense human eosinophils to the hypodense phenotype uses 3T3 fibroblasts for enhanced viability, accelerated hypodensity, and sustained antibody-dependent cytotoxicity.
Human peripheral blood-derived eosinophils were assessed for their viability, density, and functional properties after 7 days of culture with purified mouse IL-5 and mouse 3T3 fibroblasts. Whereas none of the eosinophils remained viable after 7 days of culture in the absence of IL-5, 38 +/- 12% and 61 +/- 14% (n = 6, mean +/- SD) of the eosinophils survived in the presence of 1 pM IL-5 alone or 1 pM IL-5 in the presence of 3T3 fibroblasts, respectively (p less than 0.05). Direct contact between the fibroblasts and the eosinophils was not needed for this enhanced IL-5-dependent viability. After 7 days, 66 +/- 7% (n = 6) of the cocultured eosinophils were viable when the two cell types were separated by a 0.4-microns filter. As assessed by density-gradient centrifugation after 7 days of IL-5 exposure, all of the original normodense eosinophils became hypodense. The time course of this conversion was accelerated by the presence of 3T3 fibroblasts. Enhanced helminthic cytotoxicity was maintained by the 7-day cultured eosinophils only if they had been cocultured with fibroblasts. Eosinophils killed 10 +/- 11% (n = 5), 48 +/- 17%, and 31 +/- 15% of the larvae when they were cultured for 7 days in IL-5 alone, in IL-5 in direct contact with 3T3 fibroblasts, or in IL-5 with filter separation of the fibroblasts and the eosinophils, respectively. The ability of IL-5 to induce progenitor cells to differentiate selectively into eosinophils, and of 3T3 fibroblasts to facilitate the IL-5-mediated conversion of normodense eosinophils to hypodense eosinophils with increased viability and antibody-dependent cytotoxicity suggests a role for both hematopoietic and tissue factors in determining the presence and pathobiologic function of activated hypodense eosinophils in patients with hypereosinophilic conditions.
Rothenberg
M E
ME
Department of Medicine, Harvard Medical School, Boston, MA 02115.
Petersen
J
J
Stevens
R L
RL
Silberstein
D S
DS
McKenzie
D T
DT
Austen
K F
KF
Owen
W F
WF
D000818:Animals; D000920:Antibody-Dependent Cell Cytotoxicity / Q000187:drug effects; D000001:Calcimycin / Q000494:pharmacology; D002460:Cell Line; D002469:Cell Separation; D002470:Cell Survival; D002499:Centrifugation, Density Gradient; D004804:Eosinophils / Q000276:immunology* / Q000378:metabolism / Q000502:physiology; D005347:Fibroblasts / Q000276:immunology / Q000502:physiology*; D006801:Humans; D015848:Interleukin-5; D007378:Interleukins / Q000494:pharmacology*; D007814:Larva / Q000276:immunology; D007958:Leukocyte Count; D051379:Mice; D010641:Phenotype; D013189:SRS-A / Q000378:metabolism; D012550:Schistosoma mansoni / Q000276:immunology
D015848:Interleukin-5; D007378:Interleukins; D013189:SRS-A; D000001:Calcimycin