Phencyclidine exposure alters in vitro cellular immune response parameters associated with host defense

A comparative study of immunomodulation produced by in vitro exposure to delta opioid receptor agonist peptides

The present study assessed the direct immunomodulatory effect of a panel of synthetic peptides exhibiting delta-opioid receptor agonist activity. Murine splenic lymphocytes and peritoneal macrophages were cultured in vitro with peptides at concentrations of 0.00001-10 microM. Assessment was made of B-cell function by quantitating cellular proliferation, T-cell function by measuring cytokine production, natural immunity by quantitating basal and cytokine-augmented natural killer (NK) cell activity, and macrophage function by production of IL-6. These peptides had minimal effects on B-cell proliferation at any concentration examined. In comparison, enhancement of cytokine production by T-helper cells occurred following exposure to several of the compounds, to a significant extent with DPDPE, DPDPE-trifluoroacetate, or deltorphin-1 and most pronounced at concentrations between 0.00001 and 0.1 microM. Likewise, IL-6 production by macrophages was significantly augmented by exposure to these three peptides. NK cell function was significantly enhanced by in vitro exposure to several of the peptides, with enhancement generally noted at concentrations between 0.00001 and 0.01 microM. However, some of the peptides (most notably DADLE) greatly suppressed NK cell activity. These data suggest that delta opioid agonists are broadly immunomostimulatory.

Effects of naltrexone on morphine-induced tolerance and physical dependence and changes in cellular immune function in mice

The effects of naltrexone on tolerance/dependence, as well as alterations in cellular immune function induced by morphine administration, were determined. Mice were rendered tolerant to and physically dependent on morphine by subcutaneous implantation of pellets containing 75 mg of morphine. Implantation of naltrexone pellets (10 mg) blocked the development of tolerance to the analgesic action of morphine, as well as the development of physical dependence. Morphine suppressed lymphoid organ weights and cellularities, and this suppression was blocked by naltrexone. B-Cell proliferation was suppressed in morphine-tolerant but not in morphine-abstinent mice, and this suppression was exacerbated by naltrexone. Morphine tolerance and abstinence were associated with suppression of IL-2 production, which was completely blocked by naltrexone. NK cell activity was not significantly affected by either morphine or naltrexone exposure. The results suggest that the effects of morphine on the immune system are at least partially mediated through opioid receptors.

Selective modulation of immune function resulting from in vitro exposure to methylenedioxymethamphetamine (Ecstasy)

Abuse of illicit analogs of methamphetamine (i.e., 'designer drugs') represents a growing problem. One of the most popular methamphetamine analogs is (+/-)-3,4-methylenedioxymethamphetamine (MDMA), commonly known as Ecstasy. The authors demonstrated previously that in vitro exposure to methamphetamine results in modulation of immune functional parameters necessary for host defense. The current study was performed to assess the potential direct (in vitro) immunomodulatory effect of exposure to a modified methamphetamine. Splenocytes or peritoneal macrophages from B6C3F1 mice were cultured in vitro at MDMA concentrations of 0.0001-100 microM. T-cell regulatory function was assessed by anti-CD3-mediated production of IL-2 and IL-4, B-cell function was assessed by quantitating cellular proliferation, natural immunity was assessed by quantitating natural killer (NK) cell activity, T-cell effector function was evaluated as a function of cytotoxic T-lymphocyte (CTL) activity, and macrophage function was assessed by IL-6 tumor necrosis factor (TNF) production. In vitro exposure to MDMA had no effect on B-cell proliferation at any concentration tested. In comparison, in the absence of direct cellular toxicity, production of IL-2 was enhanced at concentrations as low as 0.0001 microM. IL-4 production was not affected by exposure to any concentration of MDMA examined, suggesting a differential alteration in T-helper cell function by this compound. Basal and augmented NK cell function were enhanced at MDMA concentrations between 0.0001 and 1.0 microM when examined at an effector:target ratio of 100:1. CTL induction was significantly suppressed at a concentration of 100 microM. Finally, macrophage production of TNF was slightly suppressed at 10 and 100 microM MDMA, although this inhibition was not statistically significant.