Physiological basis for neuroimmunomodulation.

A large number of clinical and experimental observations indicate that immune responses may be modulated by the central nervous system (CNS). The immune system (IS) and CNS are known to communicate via the endocrine and the autonomic nervous systems. In this overview, we will focus on the immunomodulating role of neurotransmitters and neuropeptides. Immune cells appear to express membrane antigens similar to those of neural cells. Similarities re-enforce analogies between CNS and IS cells. The concept that the CNS modulates immune functions implies that the immune system feeds back information to the CNS. In fact, interleukins have neuroendocrine functions whether they are produced at the periphery by immune cells or at the CNS level by glial cells. Finally, the possible endocrine functions of lymphocytes are described and it is suggested that a complete regulatory loop between immune and neuro-endocrine systems exists. Studies in neuro-immunomodulation are of great importance from a theoretical point of view, the CNS-IS inter-relationships may not be considered only between the CNS and the periphery but also at the level of the immune micro-environment which may be considered as an immune-neuro-endocrine complex.