title: Arachidonic acid cytotoxicity in leukocytes: implications of oxidative stress and eicosanoid synthesis.
abstract: Arachidonic acid (AA)-induced cytotoxicity was evaluated in leukocytes: the human leukemia cell lines HL-60, Jurkat and Raji and in rat lymphocytes. Such cytotoxicity was dose- and time-dependent. At concentrations below 5 microM, AA was not toxic; at 10-400 microM, AA induced apoptosis and at concentrations beyond 400 microM, necrosis. The minimum exposure time to trigger cell death was of around 1 h, but the effect was increased by longer exposure times until 6-24 h. Apoptosis was morphologically characterized by a decrease in cell and nuclear volume, chromatin condensation and DNA fragmentation and the presence of lipid bodies, without changes in organelle integrity. Biochemically, AA-induced apoptosis was associated with internucleosomal fragmentation and caspase activation, evaluated by PARP cleavage and the use of a caspase inhibitor. Necrosis was characterized by increased cell volume, presence of loose chromatin, appearance of vacuoles, loss of membrane integrity and of the definition of organelles. The apoptotic effect of AA was studied as to oxidative-reductive imbalance and the participation of eicosanoids. Apoptotic AA treatment was accompanied by an increase in the quantity of thiobarbituric acid reactive substances (TBARS), low-level chemiluminescence and in the glutathione disulfide/reduced glutathione ratio, indicating oxidative stress. The addition of tocopherol, ascorbate, prostaglandin E2 and lipoxygenase inhibitors delayed cell death, whereas the inhibition of cyclooxygenase promoted AA-induced cell death. Cell treatment with AA was accompanied by increased cellular production of LTB4. AA, therefore, is cytotoxic at physiological and supraphysiological concentrations, causing apoptosis and necrosis. Cell treatment with apoptotic concentrations of AA involves oxidative stress and changes in eicosanoid biosynthesis.
authors.affiliation: National Institute of Deafness and other Communication Disorders, National Institutes of Health, Room 4249, Building 50, 50 South Drive, Bethesda, MD 20892, USA. cpompeia@nidcd.nih.gov
authors.forename: Celine
authors.initials: C
authors.lastname: Pompeia
authors.forename: Jofre J S
authors.initials: JJ
authors.lastname: Freitas
authors.forename: Jung S
authors.initials: JS
authors.lastname: Kim
authors.forename: Szulim B
authors.initials: SB
authors.lastname: Zyngier
authors.forename: Rui
authors.initials: R
authors.lastname: Curi
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D016718:Arachidonic Acid / Q000378:metabolism / Q000633:toxicity*; D020169:Caspases / Q000187:drug effects / Q000378:metabolism; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D003603:Cytotoxins / Q000378:metabolism / Q000633:toxicity*; D053938:DNA Fragmentation / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D015777:Eicosanoids / Q000096:biosynthesis*; D019803:Glutathione Disulfide / Q000187:drug effects / Q000378:metabolism; D018922:HL-60 Cells; D006801:Humans; D019169:Jurkat Cells; D007962:Leukocytes / Q000187:drug effects* / Q000378:metabolism; D007975:Leukotriene B4 / Q000378:metabolism; D009336:Necrosis; D018384:Oxidative Stress / Q000187:drug effects* / Q000502:physiology; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D011506:Proteins / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism
chemical_list: D000975:Antioxidants; D016861:Cyclooxygenase Inhibitors; D003603:Cytotoxins; D015777:Eicosanoids; D011506:Proteins; D017392:Thiobarbituric Acid Reactive Substances; D007975:Leukotriene B4; D016718:Arachidonic Acid; C499322:Parp1 protein, rat; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D020169:Caspases; D019803:Glutathione Disulfide