Expression and functional characterization of killer whale (Orcinus orca) interleukin-6 (IL-6) and development of a competitive immunoassay

Christina Funke, Donald P. King, Jim F. McBain, Dieter Adelung, Jeffrey L Stott

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


Interleukin-6 (IL-6) is a cytokine that can reach detectable systemic levels and is a major inducer of the acute phase response. As such, clinical assays to identify this cytokine in mammalian sera are of diagnostic value. A 558 base-pair (bp) fragment of killer whale IL-6 was cloned and expressed as a 21kDa protein in Escherichia coli. Biological activity of the recombinant killer whale IL-6 (rkwIL-6) was demonstrated using the IL-6-dependent B9 mouse hybridoma cell line; acute phase sera from a killer whale and supernatants from lipopolysaccharide (LPS)-stimulated killer whale peripheral blood mononuclear cells (PBMCs) also supported the proliferation of the B9 hybridoma. Rat anti-mouse IL-6 receptor antibody effectively blocked biological activity of all three sources of IL-6. Polyclonal antisera, specific for the recombinant protein, were obtained by successive immunization of a rabbit with rkwIL-6. The polyclonal antibody was capable of neutralizing the biological activity of both recombinant and native kwIL-6. A competitive enzyme-linked immunosorbent assay (ELISA) was developed using the polyclonal rabbit anti-rkwIL-6 and the recombinant protein; sensitivity of the assay was in the range of 1ng/ml. The ELISA was subsequently used to identify the presence of native IL-6 in acute phase sera of two species of delphinidae, a killer whale and a bottlenose dolphin. The application of quantitative cytokine assays as diagnostic tools for monitoring cetacean health are becoming feasible as many animals are now being trained for fluke presentation, making blood collection a routine procedure.

Original languageEnglish (US)
Pages (from-to)69-79
Number of pages11
JournalVeterinary Immunology and Immunopathology
Issue number1-2
StatePublished - May 30 2003


  • Immunoassay
  • Inflammation
  • Interleukin-6 (IL-6)
  • Killer whale
  • Recombinant cytokine

ASJC Scopus subject areas

  • Animal Science and Zoology
  • Immunology
  • veterinary(all)


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