When an antigen such as a enters the body, the immune system responds in two ways. The nonspecific response mobilizes white blood cells to surround and destroy the invading antigens. Those white bloods cells release to attract other white blood cells to the area; to increase to the area, which increases redness and ; and to induce capillaries to become leaky, which creates swelling and pain. The specific immune response also mobilizes by using or B cells and T cells found in the lymph system of the body. The B cells release that bind to the antigen and target it for destruction. Other cells, called T cells, work in four different ways. One type of T cell kills the virus-infected cells in the body. Another T cell, called the helper T-cell secretes cytokines that attract antibodies, killer T cells, and other cells which destroy the virus. Once the virus has been destroyed, turn off the specific immune response. Finally, memory T and B cells are created. These cells will recognize the virus if it appears again and the specific immune response will be able to respond quickly and efficiently. The ability of our immune system to remember a virus and eliminate it is called . contain weakened forms of the virus that are introduced to the body in order to stimulate the specific immune response and create antibodies, memory B cells, and memory T cells so that the virus will not be able to infect the body in the future.