Identification, molecular characterization and functional analysis of interleukin (IL)-2 and IL-2like (IL-2L) cytokines in sea bass (Dicentrarchus labrax L.)

Francesco Buonocore* (Corresponding Author), Marco Gerdol, Alberto Pallavicini, Valentina Stocchi, Elisa Randelli, Maria Cristina Belardinelli, Andrea Miccoli, Paolo Roberto Saraceni, Christopher J. Secombes, Giuseppe Scapigliati, Tiehui Wang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)
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In mammals, interleukin (IL)-2, initially known as a T-cell grow factor, is an
immunomodulatory cytokine involved in the proliferation of T cells upon antigen activation. In bony fish, some IL-2 orthologs have been identified, but, recently, an additional IL-2like (IL-2L) gene has been found. In this paper, we report the presence of these two divergent IL48 2 isoforms in sea bass (Dicentrarchus labrax L.). Genomic analyses revealed that they originated from a gene duplication event, as happened in most percomorphs. These two IL-2 paralogs show differences in the amino acid sequence and in the exon 4 size, and these features could be an indication that they bind preferentially to different specific IL-2 receptors. Sea bass IL-2 paralogs are highly expressed in gut and spleen, which are tissues and organs involved in fish T cell immune functions, and the two cytokines could be up regulated by both PHA stimulation and vaccination with a bacterial vaccine, with IL-2L being more inducible. To investigate the functional activities of sea bass IL-2 and IL-2L we produced the corresponding recombinant molecules in E. coli and used them to in vitro stimulate HK and spleen leukocytes. IL-2L is able to up-regulate the expression of markers related to different T cell subsets (Th1, Th2 and Th17) and to Treg cells in HK, whereas it has little effect in spleen. IL-2 is not active on these markers in HK, but shows an effect on Th1 markers in spleen. Finally, the stimulation with recombinant IL-2 and IL-2L is also able to induce in vitro proliferation of HK- and spleen-derived leukocytes. In conclusion, we have demonstrated that sea bass possess two IL-2 paralogs that likely have an important role in regulating T cell development in this species and that show distinct bioactivities.
Original languageEnglish
Article number154898
Number of pages13
Early online date6 Nov 2019
Publication statusPublished - Feb 2020


  • interleukin-2
  • sea bass
  • expression
  • bioactivity
  • T cell development
  • Interleukin-2
  • Expression
  • Bioactivity
  • Sea bass


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