Effect of mild chronic stress, as a model of depression, on the immunoreactivity of C57BL/6 mice

Numerous studies correlate the state of depression with some abnormalities in the immune response, such as increased numbers of white blood-cells, alt erations in sub-populations of leucocytes, suppression of cytotoxic activit y of natural-killer cells, increased levels of some autoantibodies and acut e-phase proteins. Some of these changes have been attributed to autoimmunol ogical reactions. While the possibilities to evaluate some reactions in dep ressed patients are limited, an animal model of depression could well simul ate this clinical situation, and the chronic mild state of stress is a well accepted one. After undergoing stress for three-weeks, C57BL/6 mice demons trate in the present study a decrease in thymus weight, as well as increase d interleukin-l and decreased interleukin-2 production. Splenocytes of the depressed mice exert a decrease in natural-killer-cell activity, in the pro liferative response to Concanavalin-A, interleukin-l and anti-CD3 monoclona l antibodies and an increase in the proliferative response to lipopolysacch arides and pokeweed mitogens. Our results also suggest that chronic stress- induced activation of suppressor cells in the spleen, due to elimination of CD8(+) cells, increase the proliferation of splenocytes in response to mit ogens of T cells. (C) 1998 International Society for Immunopharmacology. Pu blished by Elsevier Science Ltd.