[Effects of stress on allergic reaction]

The purpose of the present study was to investigate the effects of stress on allergic reaction. We studied changes in the contact hypersensitivity reaction (CHR) of mice exposed to foot shock (FS) stress or psychological (PSY) stress induced by the communication box. CHR was elicited by applying antigen (2,4-dinitrofluorobenzene, DNFB) to the ear of the mice at 4 days after DNFB sensitization. In acute stress experiments, DNFB-sensitized mice were exposed for 2 h to FS or PSY stress after contact challenge with DNFB. Acute FS stress significantly inhibited CHR immediately after the end of the stress period (3 h after DNFB-challenge), and a significant enhancement of the CHR was observed at 5 h after DNFB-challenge. The concentration of the serum corticosterone level of the mice exposed to acute FS stress significantly increased compared to the control mice, immediately after stress loading. Both CHR and serum corticosterone levels after acute PSY stress loading were almost the same as those of the control groups. The temporary decrease of the inflammatory reaction at CHR caused by acute FS stress loading may have been correlated with serum corticosterone produced by the stress, and the increase of corticosterone may act as a trigger of enhancement of the CHR (delayed-type hypersensitivity). Chronic stress experiments were designed to expose mice to FS or PSY stress 2 h daily after sensitization with DNFB. These chronic stresses caused a significant reduction in the body weight of mice. The temporary decrease effect on the CHR of chronic FS stress-loaded mice was similar to the acute FS stress-loaded mice. In contrast, no significant enhancement of the CHR (late phase) at 24 h and 48 h after challenge was observed. Although the changes in body weight suggested that mice were influenced by chronic PSY stress, no significant difference from the control group for the CHR of mice exposed to chronic PSY stress was found, as in the case of acute PSY stress loading. The correlation between chronic PSY stress and CHR remains to be ascertained.