The discovery of opiates affecting the function of the immune system is not a new one, but it does seem to be a specific side-effect that often goes unmentioned or perhaps is one that many of us are not aware of. The importance of the immune system is undeniably critical; it fights infection and regulates the body’s ability to remain in overall health from viral and infectious elements. Without the immune system, the body is essentially “a sitting duck”, in the sense that any parasite, infection, virus or negative element in the body can attack the internet network of organs that form part of the body’s overall life support system.
A lot of addicts and recovering addicts are aware of the more common side-effects of opioid use, including the potential for nausea, dizziness, sedation, respiratory depression, constipation and others. The following extract from the Pain Physician Journal provides excellent insight into the lesser-known side-effect from opioid use which is the immunological effect of opiate use:
"The immunomodulatory effects of opioids were initially demonstrated in the 1890s when Cantacuzene showed cellular immune suppression and decreased resistance to bacterial infection in guinea pigs treated with morphine. Opioids have been implicated in the increased incidence of infections in heroin addicts and as a cofactor in the pathogenesis of human immunodeficiency virus. Interestingly, although exogenous opioids may generate immunosuppression, their endogenous counterparts (e.g., endorphins), induce immunoactivation. It is known that acute and chronic opioid administration can cause inhibitory effects on antibody and cellular immune responses, natural killer cell activity, cytokine expression, and phagocytic activity. The immunologic effects of opioids are mediated by central and peripheral mechanisms. The potential mechanism by which central opioid receptors mediate peripheral immunosuppression may involve the hypothalamic-pituitary-adrenal axis and the autonomic nervous system. Interestingly, peripheral immune cells under the influence of cytokines, may release endogenous opioids modulating analgesia and inflammatory responses. Moreover, the same cells can express opioid receptors, creating a bi-directional system whereby opioids, immune cells, and cytokines dynamically interact.
The role of different central opioid receptors in the modulation of the immune response is variable. Activation of KOR (kappa opioid receptor) and DOR (delta opioid receptor) may activate the cellular immune response, while effects of MOR (mu opioid receptor) may be more related to natural killer (NK) cell activity, cytokine secretion, and macrophage phagocytosis. Probably related to the affinity of different opioids to a particular receptor is the finding that mice injected with morphine had a biphasic immune response with an increase in polymorpho-nuclear phagocytosis, followed by a marked decrease 24 hours later. Methadone, however, in an equianalgesic dose did not affect the tested immunoparameters. In clinical practice, not all opioids have similar effects on the immune system. Particular reference needs to be made to tramadol, which enhances NK cell activity, lymphocyte proliferation, and IL-2 release compared to morphine, while buprenorphine, with its mu agonist and kappa antagonist effects, doesn’t show any effects on the immune response compared to morphine."
It is interesting that not all opiates produce the same immunosuppression-effect as noted above. However, it is important to be aware of the potential for opiate use to suppress the body’s ability to fight infection, especially for chronic pain patients who rely on opioid medications to have a better quality of life.