Neurological basis of drug dependence and its effects on the immune system.

This review summarizes some of the major points discussed by participants in the symposium session on effects of drugs of abuse on both neurologic and immune systems. Speakers in this session are acknowledged experts and biomedical scientists in the rapidly expanding field of studies of abuse drugs on immune responses, especially as related to the effects of increased susceptibility to infections, including opportunistic infections related to AIDS. The important topics specifically discussed in this session included discussion of the neurobiology of addiction in regards to cell biology of the central nervous system and altered physiological and behavioral functions. Using experimental rodent models, description of effects of heroin or cocaine, especially self administration of these drugs, on immune cell deficiency and HPA activation, was reviewed as well as effects on important proinflammatory cytokines like TNFalpha. A model system concerning acute morphine withdrawal on ex vivo immune responses by murine cells was described in detail, including effects of such withdrawal on splenocyte or macrophage responses to bacterial LPS. The chronic exposure of rodents to a drug such as cocaine or morphine was described in terms of CNS neurochemical alterations as related to immune responsiveness. The effects of the legal drug nicotine, now known to be the addictive substance of cigarette smoke, was discussed in regards to effects on both the neurologic and immunologic system in rodents in terms of antibody formation and T cell function, related to HBA activation and proinflammatory cytokine responses. It is apparent from this session, that studies concerning the impact of drugs of abuse on the brain-immune-axis and relationship to the immune system constitute a rapidly expanding area and warrant further interest of biomedical scientists.