Drugs of Abuse

Opioids and cannabinoids have been shown to modulate many different parameters of immune responses. In general, opioids and cannabinoids have been found to be immunosuppressive, both in vitro and in vivo in a variety of assays, including the response of lymphocytes to mitogens, antibody formation, activation of T cells, natural killer cell activity, and phagocytosis by macrophages and neutrophils. Drugs in these two classes have also been shown to inhibit the migration of cells from the circulatory system to areas of inflammation, including passage across the blood-brain barrier. Opioids and cannabinoids have both been shown to sensitize mice to a variety of infectious agents, which is commensurate with an immunosuppressed state. In specialized rodent models and monkeys, opioids sensitized to HIV and SIV, possibly related to their ability to cause heterologous desensitization of chemokine co-receptors for these viruses. The literature covered in this chapter supports the existence of a robust neural-immune interaction.