title: Expression of 5-lipoxygenase (5-LOX) in T lymphocytes.
abstract: 5-Lipoxygenase (5-LOX) is the key enzyme responsible for the synthesis of the biologically active leukotrienes. Its presence has been reported in cells of the myeloid lineage and B lymphocytes but has not been formally defined in T lymphocytes. In this study, we provide evidence for 5-LOX expression on both transcriptional and translational levels in highly purified peripheral blood T cells as well as in human T lymphoblastoid cell lines (MOLT4 and Jurkat). Messenger RNA (mRNA) of 5-LOX was amplified by conventional reverse transcription-polymerase chain reaction (RT-PCR; MOLT4 and Jurkat cells) and by in situ RT-PCR (T lymphocytes). 5-LOX protein expression was confirmed by Western blot and immunofluorescence studies. 5-LOX was present primarily in the cytoplasm with some nuclear localization and was translocated to the nuclear periphery after culture in a mitosis-supporting medium. Fluorescence-activated cell sorter analysis of different T-lymphocyte populations, including CD4, CD8, CD45RO, CD45RA, T helper type 2, and T-cell receptor-alphabeta and -gammadelta expressing cells, did not identify a differential distribution of the enzyme. Purified peripheral blood T lymphocytes were incapable of synthesizing leukotrienes in the absence of exogenous arachidonic acid. Jurkat cells produced leukotriene C(4) and a small amount of leukotriene B(4) in response to CD3-CD28 cross-linking. This synthesis was abolished by two inhibitors of leukotriene synthesis, MK-886 and AA-861. The presence of 5-LOX in T lymphocytes but the absence of endogenous lipoxygenase metabolite production compared to Jurkat cells may constitute a fundamental difference between resting peripheral lymphocytes and leukaemic cells.
authors.affiliation: Laboratoire de Biochimie et Génétique Moléculaire, Faculté de Médecine, Limoges, France. jeanne.moreau@unilim.fr
authors.forename: Jeanne M
authors.initials: JM
authors.lastname: Cook-Moreau
authors.forename: Yola
authors.initials: Y
authors.lastname: El-Makhour Hojeij
authors.forename: Guislaine
authors.initials: G
authors.lastname: Barrière
authors.forename: Hélène C
authors.initials: HC
authors.lastname: Rabinovitch-Chable
authors.forename: Karine S
authors.initials: KS
authors.lastname: Faucher
authors.forename: Franck G
authors.initials: FG
authors.lastname: Sturtz
authors.forename: Michel A
authors.initials: MA
authors.lastname: Rigaud
mesh_terms: D001094:Arachidonate 5-Lipoxygenase / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western / Q000379:methods; D019084:Fluorescent Antibody Technique, Indirect / Q000379:methods; D006801:Humans; D019169:Jurkat Cells; D012333:RNA, Messenger / Q000235:genetics; D012334:RNA, Neoplasm / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013601:T-Lymphocytes / Q000201:enzymology*; D014407:Tumor Cells, Cultured
chemical_list: D012333:RNA, Messenger; D012334:RNA, Neoplasm; D001094:Arachidonate 5-Lipoxygenase