Effects of Drugs of Abuse on Cytokine Responses

In the United States, the association between drugs of abuse and increased risk of infection has been suspected since colonial times. More recent studies have confirmed this relationship for most commonly abused drugs. Studies in animal models and in human subjects indicate that this increased susceptibility to infection is associated with decreased effectiveness of important innate and acquired immune defense mechanisms. All of the major drugs of abuse have been reported to affect cytokine and chemokine responses, which are critical in resistance to most infections. In general, proinflammatory, proimmune cytokine responses are decreased and anti-inflammatory, immunosuppressive cytokine responses are increased. The mechanisms by which this occurs have not been fully delineated, but receptor mediated effects, which probably act by interfering with immune stimulus-mediated signaling and indirect effects mediated by stress hormones, clearly are involved in the action of most drugs of abuse.