1-imm. AYÞE ALTINTAÞ

the size of the thymus was profoundly influenced by emotional events and by neurodocrine aberrations. Hans Selye discovered (1936) that when the hypothalamuspituitary-adrenal axis is activated, it leads to the rapid involution of the thymus. Following that, Andor Szentivanyi and colleagues showed (1949) the regulatory power of the nervous system over immune reactions. Cytokines, especially interleukin (IL)-2, IL6, tumor necrosis factor (TNF)-aand interferon (IFN)-g were shown to regulate the secretion of pituitary hormones during systemic immune/inflammatory reactions. It is also clear that nerves have immunoregulatory function and provide feedback signals from lymphoid organs and from sites of immune/inflammatory reactions towards the central nervous system. Now, it is well known that the nervous system plays a role in organizing, adapting and restraining the systemic inflammatory reactions via a complex cascade of mechanisms (Table 1).