Phospholipid metabolism of lymphocytes with inhibited glutathione synthesis using L-buthionine-S,R-sulfoximine.
The potential role of phospholipid metabolism in restricting lymphocyte proliferation under conditions of oxidative stress was investigated using [1-14C]-arachidonic acid (14C-AA) and 32P-orthophosphoric acid. Human peripheral blood lymphocytes (PBL) and PBL depleted of glutathione with L-buthionine-S,R-sulfoximine (BSO-PBL) were compared. The relative uniformity of glutathione depletion in the PBL population was assessed by flow cytometry. BSO-PBL were 40 to 90% depleted of glutathione 1 to 3 days after activation, respectively, and the BSO-PBL had unimpaired early activation events based on 32P-phosphatidylinositol levels. However, unlike stimulated PBL, which showed a progressive decrease in radioactivity incorporated into phosphatidylcholine and a corresponding increase into phosphatidylethanolamine, no significant differences occurred with BSO-PBL. Prelabeled BSO-PBL showed considerably more 14C radioactivity in the supernatant following 72-120 h stimulation with anti-CD3 than control PBL, which was mostly in the form of unmetabolized 14C-AA. Higher levels of leukotriene B4, 5-hydroxyeicosatetraenoate and 12-hydroxy-5,8,10-heptadecatrienoate also were observed with L-buthionine-S,R-sulfoximine treatment, which could explain the impaired proliferation obtained with a depletion of cellular glutathione. Both lysophosphatidylcholine and liberated free 14C-AA increased with L-buthionine-S,R-sulfoximine treatment following 72 h stimulation, suggesting functional impairment in the reacylating enzymes. The increased release of 14C-AA by BSO-PBL also may contribute to the imparied proliferation that occurs with loss of glutathione.
Palace
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GP
Department of Pharmacology and Toxicology, Albany Medical College, NY 12201-0509, USA.
Lawrence
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DA
D002250:Carbon Radioisotopes; D002452:Cell Count; D002851:Chromatography, High Pressure Liquid; D005434:Flow Cytometry; D005609:Free Radicals; D005978:Glutathione / Q000096:biosynthesis*; D006801:Humans; D008214:Lymphocytes / Q000378:metabolism*; D008715:Methionine / Q000031:analogs & derivatives; D018384:Oxidative Stress; D010743:Phospholipids / Q000378:metabolism*; D013997:Time Factors
D002250:Carbon Radioisotopes; D005609:Free Radicals; D010743:Phospholipids; C042415:buthionine; D008715:Methionine; D005978:Glutathione