Molecular and Functional Characterization of IL-15 in Rainbow Trout Oncorhynchus mykiss: A Potent Inducer of IFN-¿ Expression in Spleen Leukocytes

Tiehui Wang, Jason W Holland, Allison Carrington, Jun Zou, Christopher J Secombes

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89 Citations (Scopus)


IL-15 is a member of the common gamma-chain family of cytokines that possess a heterogeneous repertoire of activities on various cells of the immune system. We report here the first functional characterization of a fish IL-15 in rainbow trout. The trout IL-15 gene is 6-kb long and contains six exons and five introns that transcribe into a 1.2-kb mRNA containing seven out-of-frame AUG initiation codons and translate into a 193-aa peptide. Potential sites for transcriptional activators and repressors have been identified in the trout IL-15 gene. Like IL-15 from other species, trout IL-15 is closely linked to an INPP4B gene, but there is also a BCL10 gene located between the IL-15 and INPP4B genes. Three alternative splicing variants of the trout IL-15 gene have also been identified and their expression in vivo was studied. Trout IL-15 expression is present in all the tissues and cell lines studied. Recombinant trout IFN-gamma selectively increased IL-15 expression but had little effect on other cytokines such as IL-1 beta and IL-11. Recombinant trout IL-15 preferentially stimulated splenic leukocytes from healthy fish, where it induced a large increase in IFN-gamma expression, with little, if any, effect on IL-1 beta expression. This effect was quite long-lived, and was still apparent 24 h poststimulation. Although the exact cell types being affected have still to be determined, it is clear that once produced IL-15 will have a profound affect on the ability of the fish immune system to activate antimicrobial defenses and genes induced themselves by IFN-gamma.

Original languageEnglish
Pages (from-to)1475-1488
Number of pages14
JournalThe Journal of Immunology
Issue number3
Publication statusPublished - 1 Aug 2007


  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Cell Line
  • Cloning, Molecular
  • Female
  • Interferon-gamma
  • Interleukin-15
  • Leukocytes
  • Molecular Sequence Data
  • Oncorhynchus mykiss
  • Organ Specificity
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • Spleen
  • Interleukin-15 messenger-RNA
  • Natural-killer-cells
  • Signal peptides
  • Dendritic cells
  • Human monocytes
  • Intracellular trafficking
  • Transcription factor
  • Langerhans Cells


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