The experiments described here show that production of serum antibody
to a defined protein antigen (hen eggwhite lysozyme) can be elicited b
y classical Pavlovian conditioning in Wistar rats. Reexposure of anima
ls to a gustatory conditioned stimulus that had previously been paired
with antigen induces a reliable increase in antibody production. This
conditioned production of antibodies of IgM and IgG isotypes is simil
ar to that found in secondary responses elicited by reinjection of ant
igen. These findings demonstrate that the immune system can be stimula
ted to produce apparently normal antibody responses by a simple behavi
oral paradigm. (C) 1995 Academic Press, Inc.