Requirement of dual stimulation by homologous recombinant IL-2 and recombinant IL-12 for the in vitro production of interferon gamma by canine peripheral blood mononuclear cells

Background Very few studies have been carried out so far aiming at modulating cellular immune responses in dogs. In this study, we evaluated the ability of recombinant canine IL-2 (rcaIL-2) and IL-12, in the form of a single-chain fusion protein (rsccaIL-12), to stimulate peripheral blood mononuclear cells (PBMC) of healthy mongrel dogs. Results Recombinant canine IL-2 purified from Escherichia coli or present in the supernatant of COS-7 cells transfected with pcDNA3.1-caIL-2 (COS-7 caIL-2 supernatant) was able to induce proliferation of CTLL-2 cells, thus showing their functional activity. In addition, purified rcaIL-2 and COS-7 caIL-2 supernatant stimulated resting canine PBMC proliferation to a level higher than baseline level. Neither COS-7 sccaIL-12 supernatant nor COS-7 caIL-2 supernatant alone was able to induce significant production of interferon gamma by resting PBMC. However, COS-7 sccaIL-12 supernatant in combination with COS-7 caIL-2 supernatant induced production of IFN-γ by those cells. Conclusions The data shown herein suggest that the combination of canine recombinant IL-12 and IL-2 can be useful to promote cellular immune responses in dogs.