Lymphocyte activation T lymphocytes are produced by the bone marrow, enter the bloodstream and then travel to the thymus where they are processed through a certain procedure. When T cells leave the thymus, they are able to respond selectively to surrounding stimuli. t cells undergo a metamorphosis after coming into contact with a heterogeneous protein or antigen and passing through a series of steps: the T cell morphology becomes larger and begins to divide. This process is caused by the production of the cytokine interleukin 2 (also known as T-cell growth factor). Following this, T cells differentiate into helper cells, suppressor cells, effector cells (which make cytokines) and cytotoxic or killer cells, and promote the formation of B lymphocytes. Some B cells become plasma cells to make immunoglobulins or antibodies. A small number of T cells can survive for many years and function as memory cells for the immune system. When the body is exposed to the same antigens as before, the memory cells can initiate an effective and rapid immune response. Shenzhen Futian People’s Hospital Xiangmi Lake Branch, Zhizhong Ye Summary The inflammatory process involves an extremely complex series of immunological chain reactions. Among them neutrophils, monocytes-macrophages, lymphocytes and many cytokines, adhesion molecules and the complement and antibody systems are involved. Lymphocytes migrate to the thymus and transform into T cells, which recognize antigenic signals on the surface of monocytes or macrophages and therefore trigger or quench inflammatory processes as well as killing processes. Some B cells become plasma cells to produce immunoglobulins and enter the blood circulation. Immunoglobulins G, A, M, D and E also help the body to destroy allosteric substances. All of these processes can be facilitated or enhanced by cytokines, complement and other mediators.