The production and bioactivity of rainbow trout (Oncorhynchus mykiss) recombinant IL-1β

The predicted rainbow trout mature interleukin-1β (IL-1β) peptide has been produced as a recombinant protein in E. coli. The bioactivity of this molecule has been studied using trout head kidney cell preparations and a trout macrophage cell line (RTS11). Trout rIL-1β was shown to increase the expression level of IL-1β, cyclooxygenase (COX2) and MHC class II β chain transcription, as determined by Northern blot analysis. Stimulatory doses of rIL-1β were typically ≥10 ng/ml. Induction of IL-1β expression occurred within 1 h post-stimulation with trout rIL-1β and was maximal 3–6 h post-stimulation. Trout rIL-1β was also able to increase murine D10.G4.1 cell proliferation and trout head kidney leukocyte phagocytic activity, in a dose-dependent manner. However, equivalent D10.G4.1 cell proliferation was induced with approximately 1000-fold lower doses of human rIL-1β. That LPS contamination did not contribute to the effects seen was confirmed by determining its concentration in the trout rIL-1β preparation, and demonstrating that the rIL-1β activity was inhibited by heating or pre-incubation with a polyclonal anti-trout rIL-1β antibody.