Enhancement of Antigen-Specific Humoral and Cell-Mediated Immunity by Electric Footshock Stress in Rats

Abstract

The effect of footshock stress on the induction phase of sensitization to keyhole limpet hemocyanin (KLH) introduced intraperitoneally was studied in adult male Sprague– Dawley rats. Rats were shocked at Days −1, 0, 1, and 3 relative to sensitization with 50 μg KLH and 14 days later were intradermally injected with 25 μg KLH or were noninjected. Anti-KLH IgG levels were measured in serum by ELISA and were enhanced in stressed versus control rats shocked on Days 0 or 1; splenocyte proliferation to KLH in vitro was also found to be enhanced in shocked rats compared to that in nonshocked rats. Skin at the challenge sites was removed and histologically examined for infiltrate density. There was an increased infiltrate in animals shocked on Days 0 or 1 in comparison to nonshocked controls. The increased humoral and cell-mediated anti-KLH immunity in stressed rats is evidence for enhanced immune function by exposure to footshock proximal to the induction phase of the immune response. The possibility of a generalized increase in immune function in stressed rats is doubtful since splenocyte proliferation to the T-cell mitogens concanavalin A (Con A) and phytohemagglutinin and the B-cell mitogen lipopolysaccharide showed no alteration between control and stressed rats at the time of sacrifice.