[Age-dependent changes of stress-related immunosuppression]

The present investigations on the influence of physical stress and physical training and on the influence of aging on 19-S-antibody producing spleen cells showed: 1. Physical stress causes a failing of immunity in mice, which had no training. The immune response can be diminished by physical stress before and after sensitization. The immunosuppressive effect of stress is greater, if it was placed after sensitization. There is a strict correlation between the immunosuppressive effect of physical stress and the time of maximum production of 19-S-antibodies. 2. The immunosuppressive effect of physical stress increases with increasing age. The protecting effect of physical training is lower in adult and old animals than in young mice. 3. There is an increase of antibody loaded spleen cells until an age of eight months. In elder mice the number of immunocytes decreases significantly. 4. The mortality rate is greater in stressed and trained young mice than in the adult and old animals. Supposing a better adaptation in young mice it is to be considered that the biologically better developed animals survived by selections.