The influence of mouse housing density on autoimmune reactivity

Splenic cells from C57BL/6 mice housed in groups (six per cage) or individually (one per cage) were analyzed for their ability to synthesize autoantibodies against autologous bromelain-treated erythrocytes. Group-housed male mice had a significantly lower number of autoimmune plaque forming cells (APFC) in their spleens than age matched female mice housed under similar conditions. However, when male mice were housed individually for 4 to 44 weeks, a marked increase in numbers of APFC were found in their spleens, approaching those of female control mice. Our results demonstrate that a simple environmental manipulation such as housing conditions can profoundly modulate autoimmune reactivity. Thus, alteration of the psychophysiological state determined by the quality of housing may significantly affect the development of autoimmune disease.