CD4⁺ effector T cell distribution in vivo: TGF-β 1/TGF-β receptor II interaction during activation mediates accumulation in the target tissue by preferential proliferation

CD4⁺ effector T cells generated in mesenteric lymph nodes (mLN) leave into the blood. Although they enter many tissues, mLN effector T cells are later found preferentially in the gut, the drainage area of mLN. We show in the rat that this is not an intrinsic property of mLN T cells. Instead, within the mLN milieu T cells are instructed by cytokines such as transforming growth factor β1 (TGF-β1) to up-regulate TGF-β receptor II (TGF-βRII) during activation. This enables effector T cells to continue proliferation upon subsequent contact with TGF-β1 in mLN and gut, and to accumulate in the lymph node draining area, the most likely site of pathogen invasion.