Buprenorphine produces naltrexone reversible alterations of immune status.

Substantial evidence demonstrates that administration of high efficacy mu opioid agonists such as morphine modulate the immune response in a dose-dependent and pharmacologically specific manner, indicating functional interactions between the opioid and immune systems. In contrast to the well-characterized immunomodulatory effects of high efficacy mu opioids, little is known about how these effects generalize to other clinically employed opioids and agonists of varying degrees of mu opioid receptor stimulation. Buprenorphine is a mu opioid agonist of intermediate efficacy that is used clinically for pain management and has recently been approved for the treatment of opioid dependence. Recent evidence indicates pharmacological and mechanistic differences between buprenorphine and morphine. Therefore, the aim of the present study was to investigate whether buprenorphine also possesses immunomodulatory properties. The results demonstrate that buprenorphine dose-dependently suppresses splenic natural killer cell activity, lymphocyte proliferation and IFN-gamma production in rats in a naltrexone reversible manner, demonstrating pharmacological specificity of buprenorphine-induced immune alterations.