Opioids, immunology, and host defenses of intravenous drug abusers

Heroin addicts present with an altered and functionally impaired immune system and have a higher prevalence of infectious diseases than do nonaddicts. Individuals exposed to opioids either for pain management during surgical procedures or maintained on oral methadone for treatment of drug addiction may show either no effect or immune system suppression. Animal models have provided investigators a means to study the effects of opioids in a complex, biologic system that can be easily manipulated and controlled. This article presents the data demonstrating the effect of opioids on the immune system in humans and gives a brief overview of studies in animal models to help explain the underlying mechanisms.