Abstract
We present evidence that murine spleen cells produce a T-cell growth-stimulating factor following oxidation by periodic acid (H5IO6). The identification of this factor as interleukin 2 (IL-2) is indicated by its ability to support the growth of the IL-2-dependent CT6 cell line. In addition, preliminary analysis shows that H5IO6-stimulated growth factor has biochemical properties similar to IL-2. The time course of H5IO6-induced IL-2-like production by spleen cells was determined. No growth-stimulating activity was detected after 1 h of culture. The peak of periodic acid-induced IL-2-like production was between 18 and 24 h, while the maximum 3H-thymidine incorporation in spleen cells occurred at 72 h. Flow cytometry of CT6 cells was used for cell cycle analysis and to demonstrate their stimulation by IL-2-containing supernatants. These results were in agreement with the 3H-thymidine incorporation data. Electron microscopy of CT6 cells stimulated by supernatants from concanavalin A- or H5lO6-treated spleen cells showed no differences in their morphology. Degradation of spleen cell sialic acid prior to periodic acid oxidation inhibited IL-2-like production by 84% and inhibited 3H-thymidine uptake by 80%.
