Search

Allogeneic cytotoxic T-lymphocyte (CTL) response can be obtained following immunization of BALB/c mice with C57BL/6 spleen cells. We investigated the possibility of behaviorally conditioning this response by associating the C57BL/6 spleen cell immunization [unconditioned stimulus (US)] with camphor odor [conditioned stimulus (CS)]. We reported the possible mechanisms involved in the conditioning of natural killer cell activity. Similar approaches were used to investigate the mechanisms that participate in the conditioned CTL activity. The first mechanism of investigation utilized opioid receptor blockers naltrexone and quaternary naltrexone. Naltrexone, which blocks both the central and peripheral opioid receptors, blocked the recall of the conditioned response, whereas quaternary naltrexone, which does not penetrate the blood-brain barrier, was unable to block the conditioned response, demonstrating that centrally located opioid receptors play a role in the recall of the conditioned response. The studies are of interest because they indicate that resistance or susceptibility to various diseases such as cancer, autoimmunity, and infectious diseases might be influenced by the regulatory network of the CNS.

We hypothesize that a number of host defense responses such as natural killer (NK) cell activity, cytotoxic lymphocyte (CTL) activity, antibody production, and elevated body temperature (TR) might be conditionable. We have designated such specifically learned response to be a defensive reflex response. Here we describe a simple single trial association paradigm for conditioning the TR response in BALB/c mice. Animals are conditioned on day 0 by exposing them to the odor of camphor for 1 hr, followed by injection of the pyrogen poly I:C 20 microgram ip. Control groups are injected with either poly I:C or saline and not exposed to the camphor odor. Reexposure of all groups to the conditioned stimulus (CS) on day 2 or 3 cause elevation of body temperature in the conditioned group mice but not in the nonconditioned or saline control groups. Since we have conditioned the natural killer cell response with the same paradigm, these results suggest that multiple defensive responses might be conditionable simultaneously and they might have important survival value for the species.