Endocrine regulation of the immune system.

Immunoregulation, the major process of self-defence, appears to be more complex than has been previously thought, involving the central nervous and endocrine systems. This review demonstrates growing evidence for the hypothesis that endocrine factors from the pituitary and hypothalamus directly influence the development and function of the immune system. Both pituitary and hypothalamic hormones interfere with lymphocyte proliferation and function. Proliferation of T-lymphocytes as well as production of immunoglobulins by plasma cells seem to be hormone dependent. Clinical observations suggest that hematological, oncological, and immunological disorders known for their immune pathogenesis are associated with alterations of the endocrine homeostasis. Recently, human peripheral mononuclear cells have been shown to possess specific receptors for pituitary hormones. It is hypothesized that proteohormones act directly on lymphocytes via specific membrane receptors. Thus, the endocrine system, closely related to cortical and subcortical centers in the central nervous system, is one of the body's instruments to regulate and modulate its immune response. This hypothesized immunoregulatory pathway via the central nervous system and endocrine glands may well be of importance for the body's defence against infectious and malignant diseases. In addition, a new picture of the complex immunoregulatory mechanisms emerges for a better understanding of the function of the immune system. However, there is no single hormone which has yet been identified as being crucial for development and/or function of the immune system. It appears from the literature that a number of various proteohormones rather than a single hormone acts on immunocompetent cells.