Figure 1: Tolerogenic activity of T-regulatory cells. Tregs, express CD25 on their surface, are low in CD127, have intracellular CTLA-4. They interact with antigen presenting cell via CD-86/CD80 pathway by the phenomenon of transendocytosis. They block rejection by blocking the receptors on the surface of neighbouring effector /cytotoxic T-cells/ macrophages through the phenomenon of linked suppression, and modulating the production of cytokines interleukin-10 and tumor growth factor-beta. They convert these cells in to regulatory T cells which in turn continue this process of “infectious tolerance”.