Expression of Recombinant Porcine Interleukin-2 and Application of Its Antibody to Immunoassays

Interleukin-2 plays an important role in T lymphocyte proliferation and immune response regulations. In this study, porcine IL-2 cDNA was cloned from peripheral blood mononuclear cells, and recombinant porcine IL-2 (rpIL-2) was expressed in Escherichia coli. The size of rpIL-2 without signal peptides was about 15 kDa when determined by SDS-PAGE and Western blotting analysis. Anti-rpIL-2 antibody was produced from mice immunized with the purified rpIL-2, and its specificity was examined by Western blotting and ELISA. In the Western blotting assay, anti-rpIL-2 and anti-recombinant human IL-2 (rhIL-2) antibodies specifically recognized rpIL-2 and rhIL-2, respectively. However, anti-rpIL-2 antibody did not recognize rhIL-2, and anti-rhIL-2 antibody also did not react with rpIL-2 in the same assay. In ELISA, anti-rpIL-2 antibody strongly interacted with both rpIL-2 and rhIL-2, and anti-rhIL-2 antibody also efficiently recognized both proteins. Taken together, the specificity of anti-rpIL-2 antibody for rpIL-2 was demonstrated by Western blotting and ELISA. It was also shown that ELISA is more efficient than Western blotting in determining the species cross-reactivity of anti-rpIL-2 antibody.