Associative learning and regulation of immune responses

Conventional genetically inbred mice were exposed to an immunologically inert stimulus (CS) along with a stimulus known to perturb immune functioning [either non-specifically, an immunosuppressive drug; or specifically, an antigen]. After repeated trials of this type subsequent re-exposure of such "conditioned mice" to the CS alone was found to produce a change in immune response potential. This phenomenon has been examined in situations as diverse as those in which the test antigenic challenge is a tumour cell innoculum, or a tissue allograft. Some possible clinical implications of these findings are discussed.