Comparison of the biological properties of purified natural and recombinant human interleukin-2

We compared the biological properties of the purified recombinant human IL-2 derived from E. coli with those of purified natural IL-2. Both had almost the same specific in vitro activities on a weight basis to (i) support long-term proliferation of IL-2 dependent human peripheral blood lymphocytes, a mouse killer T cell line, and a mouse natural killer cell line; (ii) induce killer cells in normal mouse spleen cells; and (iii) induce antibody forming cells in nude mouse spleen cells. No differences in these biological activities were found between two forms of natural IL-2 that were separable by reverse phase high performance liquid chromatography.