Abstract
In clinical transplantation, the occurrence of cyclosporin A (CsA)-resistant production of IL-2 in vitro correlates with graft rejection in vivo. In this study we investigated the role of the costimulatory molecules CD28 and LFA-1 in this process in the setting of TCR-induced proliferation of primary T lymphocytes in vitro. Co-stimulation with ICAM-1 and B7.2 led to strong and CsA-resistant proliferation, which was found to be largely IL-2 dependent. All of the known calcineurin-dependent events, such as induction of NF-AT and NF-kappaB or stress-activated protein kinase activation, were markedly modulated by CsA independently of costimulation. In contrast, both ICAM-1 and B7.2 enhanced the half-life of the inducible IL-2 transcript in a CsA-resistant manner. LFA-1- but not CD28-induced IL-2 mRNA stabilization required the integrity of the actin-based cytoskeleton, suggesting that the two costimulatory molecules impact on qualitatively different signaling pathways. This is further suggested by the demonstration that LFA-1 and CD28 acted synergistically to confer CsA resistance in a model of co-stimulation using superantigen-pulsed dendritic cells. We propose that IL-2 transcript accumulation and subsequent T cell proliferation at the low transcriptional rate imposed by CsA are the result of co-stimulation-dependent stabilization of IL-2 mRNA.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Antigens, CD / immunology
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B7-2 Antigen
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CD28 Antigens / immunology*
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Calcineurin / physiology
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Cells, Cultured
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Cyclosporine / pharmacology*
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Cytoskeleton / metabolism
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DNA-Binding Proteins / metabolism
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Dendritic Cells / immunology
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Drug Synergism
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Humans
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Intercellular Adhesion Molecule-1 / immunology
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Interleukin-2 / biosynthesis
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Interleukin-2 / genetics*
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Interleukin-2 / immunology
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Lymphocyte Activation / drug effects
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Lymphocyte Function-Associated Antigen-1 / immunology*
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Membrane Glycoproteins / immunology
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Mitogen-Activated Protein Kinases / antagonists & inhibitors
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Mitogen-Activated Protein Kinases / metabolism
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NF-kappa B / metabolism
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NFATC Transcription Factors
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Nuclear Proteins*
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Promoter Regions, Genetic / genetics
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Protein Binding / drug effects
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RNA Stability / drug effects*
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RNA, Messenger / genetics
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RNA, Messenger / metabolism
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Signal Transduction / drug effects*
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Superantigens / immunology
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T-Lymphocytes / cytology
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T-Lymphocytes / drug effects*
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T-Lymphocytes / immunology
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T-Lymphocytes / metabolism
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Transcription Factors / metabolism
Substances
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Antigens, CD
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B7-2 Antigen
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CD28 Antigens
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CD86 protein, human
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DNA-Binding Proteins
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Interleukin-2
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Lymphocyte Function-Associated Antigen-1
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Membrane Glycoproteins
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NF-kappa B
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NFATC Transcription Factors
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Nuclear Proteins
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RNA, Messenger
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Superantigens
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Transcription Factors
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Intercellular Adhesion Molecule-1
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Cyclosporine
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Mitogen-Activated Protein Kinases
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Calcineurin