Migration and function of antigen-primed nonpolarized T lymphocytes in vivo

Upon antigenic stimulation, naive T lymphocytes proliferate and a fraction of the activated cells acquire a T helper cell type 1 (Th1) or Th2 phenotyp e as well as the capacity to migrate to inflamed tissues. However, the anti gen-primed T cells that receive a short T cell receptor (TCR) stimulation d o not acquire effector function and remain in a nonpolarized state. Using T CR transgenic CD4(+) T cells in an adoptive transfer system, we compared th e in vivo migratory capacities of naive, nonpolarized, Th1 or Th2 cells. Al though all cell types migrated to the spleen, only naive and nonpolarized T cells efficiently migrated to lymph nodes. In addition Th1, but not Th2, m igrated to inflamed tissues. In the lymph nodes, nonpolarized T cells proli ferated and acquired effector function in response to antigenic stimulation , displaying lower activation threshold and faster kinetics compared with n aive T cells. These results suggest that nonpolarized T cells are in an int ermediate state of differentiation characterized by lymph node homing capac ity and increased responsiveness that allows them to mount a prompt and eff ective secondary response.