Modulation of autoimmune diseases by nitric oxide.

Nitric oxide (NO) is an intercellular messenger that performs a number of functions, including neurotransmission, vasodilatation, inhibition of platelet aggregation, and modulation of leukocyte adhesion. NO has recently been shown to act as a potent cytotoxic effector molecule as well as to play an important role in the pathogenesis of organ-specific autoimmunity. NO may also modulate the immune response by interfering with Th1/Th2 balance in autoimmune diseases. This review will discuss the role of NO and nitric oxide synthase (NOS) in pathophysiologic and therapeutic implications in various autoimmune diseases with particular reference to T helper-1 (Th1) and T helper-2 (Th2) cytokines.