Immuno-suppressive lymphocyte factors. I. Purification of inhibitor of DNA synthesis to homogeneity.

Abstract

Inhibitor of DNA synthesis (IDS) is a T-lymphocyte factor, whose role in immunnoregulation might be to nonspecifically suppress the immune system especially in situations where very high, prolonged tolerogenic doses of antigens are present. We have purified IDS-contained supernates of stimulated lymphocytes to homogeneity, through isoelectric focusing and Sephadex gel chromatography. IDS has an isoelectric point of 2.73-2.75 and in its monomeric form has a mol wt of 20,000 but exists in the supernate usually as an aggregated tetrameric form. Di- and trimeric forms are also seen. All forms are biologically active. Purity was confirmed by SDS gel electrophoresis and the binding of dansyl chloride to terminal or free amino groups of proteins and peptides. We have, further confirmed that pure IDS is not cytotoxic and is probably a glycoprotein whose activity depends on an intact carbohydrate moiety.

Generation of Concanavalin A-Induced Suppressor Cells in the Cat

“…These include soluble immune sup pressor supernatant (SISS) [31], soluble suppressor factor [12], inhibitor of DNA synthesis (IDS) [32], sol uble immune response suppressor (SIRS) [33], and SIRS-like supernatant [25], Attemps to identify a sol uble mediator of suppression in the cat were unsuc cessful. The inability to identify a soluble factor could not be attributed to an absence of suppressor cells due to prolonged incubation, because the cells from which the supernatants were derived were found to actively suppress proliferation at the time the supernatants were collected.…”

“…Many of the studies investigating the mechanisms of suppression by these cells have identified soluble factors which mediate this response [12,20,25,[31][32][33]. Other studies have focused on identifying the nature of the suppressor cell itself [28,[34][35], Previous work with the inducible suppressor cell system had been done exclusively in humans and mice.…”