Environmental enrichment augments the efficacy of idiotype vaccination for B-cell lymphoma.

Environmental enrichment is known to positively influence the organism's psychologic and physiologic well-being. However, the effects of environmental enrichment on immune responses and cancer prognosis have not been clearly established and its impact on cancer therapy is unknown. Here, we report that environmental enrichment mediated a statistically significant improvement of the outcome of immunotherapy in an experimental model of B-cell lymphoma. When mice were immunized with an idiotype-vaccine, those maintained under enriched environmental conditions produced statistically significant higher levels of anti-idiotype antibodies and revealed more attenuated tumor growth than those housed in standard environments. Most strikingly, enriched tumor-bearing mice had statistically significant prolonged survival, with 44% of them disease-free compared with 0% in the standard rearing tumor-bearing mice. The possible mechanisms for the enhancement of immunotherapy by environmental enrichment are cognitive, physical activity, and psychologic. The demonstration of synergistic effect of cancer therapy and environmental enrichment on tumor rejection has important implication for cancer treatment.