NALTREXONE SUPPRESSES THE REJECTION OF CARDIAC TISSUE-TRANSPLANTATION

The present study demonstrates the following: 1. Transplantation of ca rdiac tissue induces an inflammatory response that ultimately leads to the rejection of the tissue by the host within 9 days; 2. Treatment w ith the opiate antagonist, naltrexone, significantly increased the sur vival of the transplanted cardiac tissue to 13 days, suggesting the in volvement of opioid signaling molecules in tissue rejection; 3. In fur ther experiments it was demonstrated that in mixed lymphocyte populati ons from different mice, the DNA synthesis inhibitor, mitomycin C, red uced the lymphocyte proliferative response as did naltrexone; 4. Mice injected with naltrexone for 10 days and given concanavalin A exhibite d a suppressed spleen lymphocyte proliferative response compared to co ntrols. Taken together, these data suggest that endogenous opioid sign als not only activate immunocytes, but also stimulate DNA synthesis. ( C) 1998 Elsevier Science Ireland Ltd.