Synthesis of biologically active interleukin 2 by Xenopus oocytes in response to poly(A)-RNA from a gibbon T-cell line.

The poly(A)-containing RNA isolated from a gibbon lymphosarcoma cell line, MLA144, known to release Interleukin 2 (IL2) was microinjected into Xenopus oocytes. The incubation medium from injected oocytes stimulated the DNA synthesis of an IL2-dependent cell culture and also maintained its viability. DNA-stimulating activity appeared in the oocyte incubation medium 6 h after injection and continued to accumulate for at least 96 h. Thymidine incorporation by the IL2-dependent cells is proportional to the concentration of oocyte incubation medium added and the IL2 activity produced by the oocytes is proportional to the amount of poly(A)-RNA injected. Incubation medium of oocytes injected with RNA from another T-cell line, 6G1, which does not produce IL2, did not contain DNA-stimulating activity. The same assay also showed that the IL2 mRNA sedimented at 14-16 S in a nondenaturing sucrose gradient. A series of monoclonal antibodies prepared against human IL2 neutralized the DNA-stimulating activity released by the injected oocytes to the same extent as they neutralized human IL2.