T cells can be directly transformed after being stimulated by antigens. Under normal circumstances, after an antigen enters the body, it will not directly combine with antibodies in the body, but will form a certain stimulation of T cells, resulting in their proliferation and differentiation, thus forming effector T cells. A small portion of these cells become memory cells, and when the subsequent antigen re-enters, it will directly respond to the transformation of effector T cells, thus generating a strong specific immune response. After the effector T cells are generated, they come into contact with the host cells and activate the lysosomal enzymes inside the target cells, causing changes in permeability and osmotic pressure, which leads to the death of the target cells and phagocytosis of the antigen by the cells.