Increased pulmonary metastases and natural killer cell activity in mice following handling

We have demonstrated that holding BALB/c female mice for two minutes per day for two weeks prior to injection of line 1, a BALB/c derived alveolar carcinoma, results in a significant increase in pulmonary metastases compared to unhandled controls. Handling did not affect splenic in vitro or in vivo natural killer (NK) cell activity but, surprisingly, was associated with increased NK cell activity in the lungs of these handled mice. These results demonstrate that a simple psychosocial manipulation may effect the metastatic process. The implications of these findings and potential mechanisms are discussed.