THE FATE OF ACTIVATED T-CELLS MIGRATING THROUGH THE BODY - RESCUE FROM APOPTOSIS IN THE TISSUE OF ORIGIN

After activation within a lymphoid tissue, T lymphocytes enter the blo od, where they circulate and then re-enter many organs. However, they predominantly end up in the tissue of origin, a phenomenon so far thou ght to be caused by organ-specific homing. We analyzed the fate of T c ells from different sources stimulated via the T cell receptor and CD2 8 and then injected intravenously into rats. Our results showed that p referential proliferation and reduced apoptosis, rather than preferent ial immigration, were responsible for the accumulation of activated T cells in the tissue of origin, explaining how immune responses can spr ead from site to site but still be restricted to certain regions. Mani pulating the life span of such cells might be a promising approach to influencing immune responses.