The induction of antigen-specific thymic regulatory cells in the mouse

Antigen-specific immunoregulation and autoimmune thyroiditis

1. Large Thy1+, CD8+ immunoregulatory cells were found in the thymus of mice 9-16 days after injection of soluble mouse thyroglobulin (without adjuvant). 2. Similar immunoregulatory cells appeared in the spleen 14-21 days after antigen administration suggesting that they were generated in the thymus and later migrated to the spleen. 3. The immunoregulatory cells were antigen-specific and attached to cognate antigen. 4. The degree of inhibition by the immunoregulatory cells differed among various inbred strains of mice and were virtually absent from SJL mice. 5. The regulatory function of the cells was strain specific in vitro and in vivo, and was restricted by both H-2 and non-H-2 haplotype. 6. By panning on antigen-coated plates, immunoregulatory cells were isolated and cell lines and clones with inhibitory function established.

Cells involved in the immune response. XXXVII. Antigen-specific suppressor cells, capable of secreting an antigen-specific suppressor factor, migrate from the thymus to the spleen following primary immunization

The splenic mononuclear cells (MNC) of rabbits 7-14 and 30-48 days following primary intravenous immunization with sheep erythrocytes generated large numbers of antibody-secreting or plaque-forming cells (PFC) in secondary immune responses induced in vitro, whereas the splenic MNC obtained from rabbits 18-30 days following primary intravenous immunization generated poor secondary immune responses (few PFC) in vitro. However, these latter splenic MNC depleted of T cells consistently generated many PFC in the secondary immune response in vitro. Furthermore, the splenic MNC of rabbits thymectomized prior to day 3 following primary intravenous immunization also generated good secondary immune responses in vitro, irrespective of the time of killing post-immunization, whereas the splenic MNC of rabbits thymectomized after day 7 following primary immunization generated poor secondary immune responses in vitro. These results indicate that the depressed ability of the splenic MNC, obtained from rabbits killed between days 18 and 30 post-primary immunization, to generate significant secondary immune responses in vitro is due to suppressor T cells. The suppressor cells are referred to as immune spleen suppressor cells or ISSC. It was demonstrated that the suppression by the ISSC is antigen-specific and that the ISSC secrete an antigen-specific suppressor factor referred to as immune spleen suppressor factor or ISSF. It is concluded that the ISSC are generated in the thymus within a few days following primary immunization, that they migrate to and infiltrate the spleen between days 3 and 7 following primary immunization, and that they suppress or down-regulate further antibody synthesis via the secretion, locally of ISSF.