Cocaine modulation in vitro of tumor necrosis factor production by macrophages from retrovirally infected mice

In vitro response of v-Ha-ras transgenic mouse lymphocytes after in vivo treatment with cocaine

Oncomouse is a transgenic mouse carrying an activated v-Ha-ras oncogene under the control of the mouse mammary tumor virus promoter. The objective of this paper was to learn if the in vitro secretion of IL-2 and IFN-gamma and the release of sIL-2R by Oncomice spleen and thymus cells depended on the presence of the oncogene product, on the in vivo pretreatment with cocaine, or on the in vitro treatment with cocaine or morphine. Oncomice thymocytes from different experimental groups released less sIL-2R than FVB thymocytes. Oncomice thymocytes secreted more IFN-gamma than FVB thymocytes. Oncomice thymocytes cultured in the presence of Con A and cocaine showed a diminished release of sIL-2R and a lower secretion of IFN-gamma, a phenomenon not observed in FVB thymocytes. IFN-gamma secretion was lower in Oncomice splenocytes. In general, Oncomice thymocytes and splenocytes responded in a nearly opposite fashion to their FVB counterparts. In this study, the in vitro response to mitogens, cocaine or morphine depended on genetic background and not on the in vivo pretreatment with cocaine. Our results emphasize the role of the v-Ha-ras oncogene in defining the host immune response.

Peripheral human T lymphocyte maintenance of immune functional capacity and phenotypic characteristics following in vivo cocaine exposure

The effects of cocaine exposure upon the host's immune response is equivocal since a variety of studies have generated conflicting conclusions, often as the result of differences between in vitro and/or animal models and the actual conditions experienced in humans who are acutely abusing this drug. To further address this issue, we have studied a group of patients who were positive for cocaine or cocaine metabolites and we evaluated a variety of functional parameters of T-lymphocytes and other peripheral lymphoid cell populations, as well as immunophenotypic characteristics of these cells. When compared to normal controls and patients who were negative for cocaine, we found that the cocaine-positive patients had T-cell functional assays which were essentially normal, with the exception of a slight depression in PHA stimulation. Likewise, the immunophenotype of the peripheral blood lymphocytic populations showed normal percentages and numbers of their T cell subsets (CD4, CD8), NK cells, and B cells. Multicolor flow cytometry analysis revealed no difference in T cell subpopulations positive for the "memory" marker, CD62L. No correlation could be established between levels of cocaine or cocaine metabolites and any phenotypic, demographic, or functional parameter. In summary, these results demonstrate that individuals acutely exposed to cocaine do not show markedly altered T cell function or fluctuations in phenotypically identified cell populations. These studies imply that acute cocaine exposure does not predispose individuals to grossly apparent immunosuppression. However, the possibility that subtle, transient, or more specific changes in the immune system may be incurred by use of cocaine, particularly with chronic exposure, remains to be determined.

Immunologic effects of cocaine in prenatally exposed rats and mice

The immunotoxicity of prenatal cocaine exposure was investigated using Sprague-Dawley rats and C57B1/6 mice. Pregnant animals were injected twice a day with cocaine or saline from gestation day 5 until the day before parturition. The immune system of the rat offspring was evaluated at 8 weeks of age by measuring the antibody response to SRBC (plaque assay and serum IgM), delayed-type hypersensitivity response to KLH, and lymphocyte subpopulations in the spleen and thymus using flow cytometry. The immune system of the mice offspring was evaluated at 4 weeks of age by measuring spleen cell proliferation in response to KLH, LPS, and alphaCD3 and IgG production to KLH. From the differences observed between cocaine exposed animals and controls, we conclude that prenatal cocaine exposure does not cause lasting detrimental effects on the immune system, but instead, may enhance B-cell responsiveness.

Effect of ethanol and cocaine treatment of the immune system of v-Ha-ras-transgenic mice

The objective was to investigate if the presence of the v-Ha-ras oncogene could induce immune changes different to the ones observed in normal mice. Therefore, we decided to use Oncomice, the transgenic mice with an activated v-Ha-ras oncogene under the control of the mouse mammary tumor virus-promoter, and their normal inbred counterparts, FVB mice. Both strains of mice were fed the Lieber-DeCarli liquid diet with ethanol or the isocaloric control diet and were injected daily with cocaine or saline. The percentage and absolute number of T and B lymphocytes in the spleen and thymus were determined. The in vitro production of TNF-alpha (tumor necrosis factor-alpha), IL-2 (interleukin-2) and IFN-gamma (interferon-gamma) by spleen cells, and the levels of serum sIL-2R (soluble IL-2 receptor) were also measured. Oncomice fed the Lieber-DeCarli ethanol diet or receiving either saline or cocaine injections presented a higher tumor incidence than Oncomice receiving the control diet. A reduced total number of thymocytes as well as absolute number of cells in all the subsets was found in Oncomice. Moreover, a decreased percentage of CD8+ cells was also observed in Oncomouse spleens. These features were even more marked in ethanol-treated Oncomice. Higher serum sIL-2R levels were observed in Oncomice, especially in mice treated with ethanol or cocaine. The results suggest that the oncogene product, P21ras, plays an important role in dysregulating the immune system and hence in favoring tumorigenesis.

Cocaine blunts human CD4+ cell activation

Cocaine is reported to be immunotoxic. The biochemical mechanisms responsible for the immunopharmacological outcomes of cocaine in vivo and in vitro remain, however, to be fully elucidated. Our experimental data confirm that exposure of normal human T cells to micromolar concentrations of cocaine modulates T-cell responses to stimulation by a variety of stimuli, and indicate that cocaine impairs early activation events during CD4+ but not CD4- T-cell stimulation. Pre-incubation of enriched CD4+ T-cell subpopulations that express the homing receptor CD62L with nanomolar concentrations of the endogenous opioid peptide beta-endorphin leads to a more severe impairment of activation than that noted following pre-incubation with micromolar concentrations of cocaine alone. These findings begin to elucidate the molecular and cellular mechanisms of the immunopathology of cocaine. Our data support the proposition that cocaine abuse may place cocaine-abuser HIV-seropositive individuals at increased risk of opportunistic infections.

Alterations of hepatic drug metabolism in mice following infection with the murine retrovirus LP-BM5

Infection of mice with the murine retrovirus mixture LP-BM5 caused a retroviral infection with many similarities to human HIV infection. We have reported alterations in hepatic drug metabolism which progressed during the course of this infection. Hexobarbital-induced sleep time increased 1.5-2.2-fold above uninfected controls after 10 to 19 weeks post infection. Inhibition of spectral cytochrome P-450 levels by 25 to 30% was observed between 15 and 17 weeks post-infection, and there were changes in specific microsomal enzyme activities. The microsomal cocaine demethylase activity was reduced by 40%, whereas cytosolic enzyme activities were increased by 1.5-2.0-fold. These alterations may contribute to the altered metabolism of drugs of abuse reported in MAIDS mice. The mechanism for these alterations is not known, although the effects correspond temporally to reported infiltration of the liver with immunoblasts and plasma cells. This suggests a role for the immune system or for mediators released by cells of the immune system which could account for these observations. An understanding of the effects of infection on drug metabolism is important because of their impact on the efficacy and safety of drugs for use in AIDS patients).