The present invention has objects to provide a novel human T-cell population having both cytotoxic and immunosuppressive activities, and to a method for preparing the same. The above objects are attained by providing a human T-cell population which is obtainable by coculturing mononuclear cells, collected from human blood, with stroma cells and which has the following features: (1) being positive for CD3, CD25, CD28 and T-cell antigen receptor ±²； (2) essentially consisting of three groups of a CD4 positive and CD8 positive (CD4 + CD8 + ) T-cell group, a CD4 positive and CD8 dimly positive (CD4 + CD8 dim ) T-cell group, and a CD4 negative and CD8 positive (CD4 - CD8 + ) T-cell group； (3) exerting a cytotoxic activity against the cocultured stroma cells； and (4) exerting an immunosuppressive activity against activated T cells.
