Endogenous factors possessing lymphoid chalone properties, purified by chromatography.

Lymphoid chalone extracts, obtained from bovine spleen were purified on chromatographic columns: in the first step of the procedure, exclusion chromatography on Sephadex G75, and ion exchange chromatography on DEAE Sephadex were applied. A purified, active material was thus obtained. Upon thin layer chromatography, this fraction was shown to contain 3-4 UV absorbing components and 2 ninhydrin positive components. Further purification on Biogel P2, on Sephadex G10 and preparative thin layer chromatography, showed that the biological activity was located in small molecular weight components which belong to the polypeptide series. The ultraviolet absorbing components were identified as known nucleosides. The purified material shows an inhibitory effect on the uptake of 3H-thymidine by lymphocytes, as well as on mitogen induced lymphocyte transformation and haemolysin plaque forming cells. Furthermore, this inhibitory effect is specific for lymphoid cells.