title: Leukotriene C4 production from human eosinophils in vitro. Role of eosinophil chemotactic factors on eosinophil activation.
abstract: We studied the role of naturally occurring eosinophil chemotactic factors on leukotriene (LT)C4 production from highly purified (87.1 +/- 2.4%) normodense eosinophils. Platelet activating factor (PAF) directly induced LTC4 production from eosinophils in a dose (10(-9) to 10(-5) M) and a time-dependent manner. PAF (10(-5) M) induced 0.74 +/- 0.08 ng of LTC4 production/10(6) eosinophils. However, lyso-PAF, eosinophil chemotactic factor of anaphylaxis, and LTB4 failed to induce LTC4 production within the tested range. Furthermore, the pre-incubation of eosinophils with 5 micrograms/ml of cytochalasin B did not alter the chemotactic factor-induced LTC4 production. When eosinophils were stimulated by the submaximal concentration (1 microgram/ml) of calcium ionophore A23187, the pre-incubation of eosinophils with 10(-6) M or 10(-5) M of PAF, or 10(-5) M of eosinophil chemotactic factor of anaphylaxis significantly enhanced LTC4 production up to 163.9 +/- 17.5% (p less than 0.05), 279.2 +/- 32.9% (p less than 0.01) and 165.2 +/- 21.2% (p less than 0.05) of the control, respectively. However, the pre-incubation with lyso-PAF or LTB4 failed to enhance A23187-induced LTC4 production. The pre-incubation of eosinophils with phosphatidyl serine also failed to enhance A23187-induced LTC4 production. However, the direct stimulation of protein kinase C by PMA enhanced the submaximal concentration of A23187-induced LTC4 production from eosinophils up to 179.5 +/- 20.9% (p less than 0.05) of the control. Our findings indicate that PAF and ECF-A work not only as chemotactic factors but also induce a functionally active state of eosinophils probably through their post-receptor mechanisms, and contribute to the inflammatory processes.
authors.affiliation: Allergic Disease Center, Creighton University School of Medicine, Omaha, NE 68178.
authors.forename: N
authors.initials: N
authors.lastname: Tamura
authors.forename: D K
authors.initials: DK
authors.lastname: Agrawal
authors.forename: R G
authors.initials: RG
authors.lastname: Townley
mesh_terms: D000328:Adult; D000001:Calcimycin; D002478:Cells, Cultured; D002630:Chemotactic Factors / Q000502:physiology*; D002631:Chemotactic Factors, Eosinophil / Q000502:physiology*; D004789:Enzyme Activation / Q000187:drug effects; D004804:Eosinophils / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D005260:Female; D006801:Humans; D007975:Leukotriene B4 / Q000502:physiology; D008297:Male; D010718:Phosphatidylserines / Q000494:pharmacology; D010972:Platelet Activating Factor / Q000502:physiology; D011493:Protein Kinase C / Q000378:metabolism; D013189:SRS-A / Q000096:biosynthesis*; D013755:Tetradecanoylphorbol Acetate
chemical_list: D002630:Chemotactic Factors; D002631:Chemotactic Factors, Eosinophil; D010718:Phosphatidylserines; D010972:Platelet Activating Factor; D013189:SRS-A; D007975:Leukotriene B4; D000001:Calcimycin; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate