Regulation of nitric oxide synthesis in infectious and autoimmune diseases.

Nitric oxide (NO) is an essential mediator for a variety of biological functions, including defence against a range of pathogens. However, excessive production of NO as a result of immunological stimulation, will lead to important immunopathologies. Therefore the production of NO is necessarily under tight regulation. The regulatory mechanisms so far known to control NO synthesis include cytokines (induction of NO synthase by IFN-gamma, TNF alpha, MIF and LPS, and down regulation by IL-4, IL-10 and TGF beta), feedback inhibition by NO itself, inhibition by pretreatment with LPS and glycoinositol-phospholipids and up regulation by lipophosphoglycan from the protozoa parasite, Leishmania major.