NEUROIMMUNOMODULATION BY OPIATES - RELATIONSHIP TO HIV-1 INFECTION AND AIDS

Opiate addiction is a major risk factor for acquired immunodeficiency disease syndrome (AIDS). Since alkaloid opiates and endogenous opioid peptides have been shown to affect immune function, there is considerable interest in understanding whether opioids themselves play any direct or indirect role in modulating expression of HIV-1 and the development of AIDS in heroin addicts. This issue is difficult to address for two main reasons. The addictive liabilities of opiates prohibit direct controlled assessments of their effects in humans and epidemiological assessments of heroin addiction are compromised by the association of addiction with a variety of interdependent milieu cofactors, aside from opiates themselves, that have the independent potential to modulate immune function and viral expression. Accordingly, experimental evidence attained through in vitro and in vivo studies with animal models and human blood cells must supplement clinical observations to obtain the best possible estimate of the potential of opiates to modify host responses to HIV-1 infection and the development of AIDS. Reviewing current evidence from this perspective indicates that there is substantial support for the notion that opiates can affect both immunological and virological processes that dictate the pathogenesis of HIV-1 infections. However, the influence exerted by opiates appears to be conditionally dependent on the stage of opiate dependency. Thus, a well-maintained opiate dependency can be beneficial to host defense systems while poorly maintained dependencies can be quite disruptive. Such information has relevance, not only to the AIDS situation per se, but, also, to therapy of drug addiction and to the field of neuroimmunomodulation in general. © 1993 Pergamon Press Ltd.