Behavioral conditioning prolongs heart allograft survival in rats.

CHANGES in immune function can be produced using behavioral conditioning. This paradigm involves the pairing of a novel flavored drinking solution (the conditioned stimulus, CS) with an immunomodulatory drug (the unconditioned stimulus, UCS). Upon subsequent re-presentation of the conditioned stimulus, alterations in immune functions similar to those following unconditioned stimulus (drug) administration are observed. We have shown that the reduction in splenocyte proliferation and alterations in blood leukocyte subset numbers induced by cyclosporine A (CsA) can be reproduced by conditioning. Therefore, we investigated whether these effects were of sufficient magnitude to prolong heart allograft survival.