Abstract: There is accumulating evidence for a strong interaction between components of the nervous system and immune system. Little is known, however, how the interaction takes place. Because multiple changes are occurring simultaneously in all organ systems, it is fairly difficult to develop an approach that allows one to study the whole organism and define the mediators of the interacting systems. Conditioned immunosuppression, a phenomenon observed and confirmed in many laboratories, may provide insight into the pathways of communication between the brain and immune system. Conditioning allows one to separate the afferent from the efferent circuits. There is now a number of laboratory models of conditioned immunosuppression using a taste aversion paradigm. Experiments have shown that a number of immunological parameters can be modified by the behavioral conditioning. The mechanisms involved in conditioned immunosuppression have not been delineated. In recent years, many studies have demonstrated that removal of sympathetic noradrenergic input to the immune system can abrogate the decreased immune response induced by the behavioral conditioning and lesion into the insular cortex and amygdala can disrupt the acquisition of conditioned immunosuppression. Moreover, it has been observed that the survival of heart allografts in rats can be prolonged by conditioned immunosuppression paradigm. These experiments suggest that behaviorally conditioned immunosuppression may have important clinical implications as an adjunct to drug treatment in transplantation medicine.

Key words: conditioned immunosuppression, paradigm, mechanism, Pavlovian conditioning of immune response