The restraint stress-induced reduction in lymphocyte cell number in lymphoid organs correlates with the suppression of in vivo antibody production

In this study, we examined the effects of restraint stress on some immune parameters such as the in vivo antibody levels, cytokine production, and lymphocyte cell number in the spleen or mesenteric lymph node (MLN). BALB/c mice were thus injected intraperitoneally 2-times with OVA absorbed into alum on days 0 and 21. Before the first injection, the animals were either restrained for 12 h (stress group) or returned to their home cage (control group). Exposure to stress resulted in a reduction in the serum levels of anti-OVA IgE, IgG1, and IgG2a. In addition, stress also caused a decrease in the IL-4 and IFN-γ levels in the spleen or mesenteric lymph node cell culture supernatants. Furthermore, exposure to stress resulted in a decrease in the splenic and mesenteric lymphocyte cell number when examined immediately after the cessation of stress. This decrease persisted for at least 12 h after the termination of stress and thereafter disappeared 24 h after stress. The stress-induced reductions in antibody and cytokine production occurred only when antigen was given either immediately or 6 h after stress, but not when antigen was given 24 h post stress. These results thus suggest that the restraint stress-induced change in lymphocyte cell number in the spleen or MLN closely correlates with the altered antibody and cytokine levels.