Stress susceptibility predicts the severity of immune depression and the failure to combat bacterial infections in chronically stressed mice.

Chronic psychological stress has been suggested to play a role in disorders in which the immune system unexpectedly fails to respond in a protective manner. Chronic combined acoustic and restraint stress compromises the anti-bacterial defense mechanisms of female BALB/c mice. The immunodeficiency is characterized by an apoptotic loss of lymphocytes, reduced ex vivo-inducibility of TNF but increased inducibility of IL10, reduced T-cell proliferation, and impaired phagocyte functions. Stressed mice develop depression-like behavior that was monitored by a stress severity score (SSS). Besides a strain (BALB/c>CBA) and gender (male>female) dependent susceptibility to chronic stress, inbred mice have an individual coping ability. Importantly, the individual SSS strongly correlates with Escherichia coli dissemination after infection as well as with IL10-inducibility and circulating corticosterone levels of each animal.