title: Cyclosporin A and FK506 reduce interleukin-5 mRNA abundance by inhibiting gene transcription.
abstract: The cytokine interleukin-5 (IL-5) selectively induces the proliferation, differentiation, and activation of mature eosinophils. The immunosuppressive agents cyclosporin A (CsA) and FK506 ameliorate the influx of eosinophils seen in allergic conditions such as asthma. We investigated the mechanisms controlling IL-5 messenger RNA (mRNA) expression in human T-lymphocytes in the presence of CsA or FK506. Fresh human peripheral blood mononuclear cells (PBMC); 7-day cultured PBMC, which represent a population of activated T-lymphocytes derived from PBMC; and the T-cell line HSB-2 were used. A novel polymerase chain reaction (PCR)-based nuclear run-on assay was employed to investigate the rate of IL-5 gene transcription. IL-5 mRNA degradation was measured by quantitative reverse transcriptase (RT)-PCR. CsA and FK506 strongly inhibited cellular IL-5 mRNA expression in response to phytohemagglutinin (PHA), or to phorbol myristate acetate (PMA), and/or calcium ionophore. Marked inhibition was observed in PBMC, 7-day cultured PBMC, and HSB-2 cells. Nuclear run-on assays done with either 7-day cultured PBMC or HSB-2 cells demonstrated striking inhibition of IL-5 gene transcription by both CsA and FK506 at levels reflecting the degree of reduction of total cellular IL-5 mRNA abundance. Neither CsA or FK506 had any detectable effect on the stability of IL-5 mRNA. Thus, the inhibitory effect of CsA and FK506 on cellular IL-5 mRNA expression can be explained by inhibition of the rate of IL-5 gene transcription.
authors.affiliation: Centre for Immunology, University of New South Wales, and St. Vincent's Hospital, Sydney, Australia.
authors.forename: F G
authors.initials: FG
authors.lastname: Rolfe
authors.forename: J E
authors.initials: JE
authors.lastname: Valentine
authors.forename: W A
authors.initials: WA
authors.lastname: Sewell
mesh_terms: D002478:Cells, Cultured; D016572:Cyclosporine / Q000494:pharmacology*; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D015848:Interleukin-5 / Q000235:genetics / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism; D016559:Tacrolimus / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects*; D014407:Tumor Cells, Cultured
chemical_list: D007166:Immunosuppressive Agents; D015848:Interleukin-5; D012333:RNA, Messenger; D016572:Cyclosporine; D016559:Tacrolimus