GROWTH-HORMONE INSULIN-LIKE GROWTH FACTOR-I AND IMMUNE FUNCTION

Growth hormone (GH) and insulinlike growth factor I (IGF-I) may be par t of a neuroendocrine immune axis that stimulates cellular proliferati on of primary lymphoid organs (bone marrow, thymus) as well as stimula tes activation of peripheral lymphocytes and macrophages to enhance sp ecific immune responses. GH can also stimulate production of thymic ho rmones and cytokines, and in this way impact on immune function. It is not clear whether GH and IGF-I act independently or whether the actio n of GH is mediated by local production of IGF-I by lymphocytes. Both GH and IGF-I and their receptors are present in lymphocytes. Thus, cel ls of the immune system may be important targets of the GH-IGF-I axis.