Alterations of Immune Functions in Heroin Addicts and Heroin Withdrawal Subjects PIYARAT GOVITRAPONG, TUNDA SUTTITUM, NAIPHINICH KOTCHABHAKDI and THONGCHAI UNEKLABH

Conflicting results, both decreased and increased, have been reported concerning the function of T-lymphocytes in heroin addicts. We investigated the alterations of T-lymphocyte proliferative responses and immunophenotypic markers on lymphoid cells in heroin addicts and during different periods of heroin withdrawal in addicted subjects. This study has demonstrated a decrease in the response of T-lymphocytes to 1.2, 2.5, 5 and 10 mg/ml of phytohemagglutinin stimuli in heroin addicts and 1to 5-day heroin withdrawal subjects compared with controls. Similarly, in an in vitro study, 10, 10 and 10 M concentrations of morphine were shown to suppress 0.6 and 2.5 mg/ml of PHA-stimulated T-lymphocyte obtained from naive subjects. This inhibitory effect of morphine on PHA stimulation was completely abolished by 100 mM naloxone. The immunological parameters of total T-lymphocytes (CD3), Thelper cells (CD4), cytotoxic T-cells (CD8), B-cells and natural killer cells that are the immunophenotypic markers studied by flow cytometric analysis were altered in heroin addicts, 15to 21-day and 6to 24-month heroin withdrawal subjects, when compared with controls. These results suggest that heroin addicts and short period (15 to 21 days and 6 to 24 months) of heroin withdrawal have decreases in their immune system functioning and that the heroin withdrawal subjects seem to gradually reverse their immunological parameters to normal levels when withdrawal was sustained $2 years. This is the first report examining immune function in heroin withdrawal subjects using the “cold turkey” method. The results are beneficial for further study of the mechanism responsible for the opioid-induced changes in immune function. Because of the AIDS epidemic, interest in studying the effects of drugs of abuse, especially opiates, on the immune system has increased greatly. This issue is now of paramount importance because of the association of AIDS with intravenous drug abuse. Heroin abusers are a high-risk group for the development of AIDS and HIV infection. Intravenous drug abusers account for 7.3% of the total AIDS cases in Thailand (Wongkhomthong et al., 1995). Indeed, the HIVseropositivity rate among intravenous drug abusers can be even greater, ranging from 5% in certain areas to 75% in others (Curran et al., 1984), and this group is generally regarded as posing the most substantial risk of furthering spread of the disease. Even in the absence of AIDS, increasing evidence indicates that chronic use of opioid drugs can affect the functioning of the immune system. Heroin addicts have an increased susceptibility to a variety of infectious diseases (Louria et al., 1967), and alterations in a wide variety of immune parameters also have been reported among them (for reviews, see Rouveix, 1992; Sibinga and Goldstein, 1988; Carr et al., 1996). A variety of changes in the immune system have been observed, indicative of both decreased and increased functioning in heroin addicts. The absolute number and percentage of total and active T lymphocytes in the peripheral blood of opiate addicts and T-cell rosette formation were significantly depressed (McDonough et al., 1980). In contrast, an increase in the absolute number of T-cells in the blood of heroin addicts who were not malnourished was reported in another study (Heathcote et al., 1981). Similar conflicting results have been reported concerning the functional activity of T lymphocytes from heroin addicts. Brown et al. (1974) found impaired in vitro responsiveness of lymphocytes to each of the three mitogens (PHA, concavanalin A, pokeweed mitogen) in heroin addicts relative to control values. Similarly, a suppressed PHA response in methadone patients was reported (Quagliata et al., 1977); but Reddy et al. (1987) found normal T-proliferative responses to both concavanalin Received for publication December 12, 1997. 1 This work was supported by a Mahidol University Research Grant (P.G.) and a Thanyarak Hospital Research Fund (T.U.). ABBREVIATIONS: PHA, phytohemagglutinin; NK, natural killer; HIV, human immunodeficiency virus; AIDS, acquired immune deficiency syndrome; HPA, hypothalamus-pituitary-adrenal; IL-1, interleukin-1; RPMI, Roswell Park Memorial Institute; DAMGO, [D-Ala,MePhe, Gly-ol]enkephalin; HBsAg, hepatitis B antigens. 0022-3565/98/2862-0883$03.00/0 THE JOURNAL OF PHARMACOLOGY AND EXPERIMENTAL THERAPEUTICS Vol. 286, No. 2 Copyright © 1998 by The American Society for Pharmacology and Experimental Therapeutics Printed in U.S.A. JPET 286:883–889, 1998 883 at A PE T Jornals on A ril 4, 2017 jpet.asjournals.org D ow nladed from A and tetanus toxoid antigen in another group of healthy addicts. Immunophenotypic markers on lymphoid cells in human addicts have been studied using flow cytometric analysis. There was a profound decrease in the T-helper/cytotoxic Tcell (CD4/CD8) ratio in heroin addicts (Donahoe et al., 1987). Shine et al. (1987) found a normal pattern of T-cell subsets and a normal CD4/CD8 ratio in another group of healthy intravenous drug abusers and methadone patients. Most of the data have suggested that opiates are involved in the cell-mediated immune responses in heroin addicts. However, data of immune responses in heroin-withdrawal subjects during various withdrawal periods are not available at this moment. Thus, the evidence for the immunomodulatory, and even the immunocompromising potential of opioids is compelling. Still, our understanding of the effects of opioids on the immune system is incomplete. Controversial results, in part, may be due to the specific mechanisms responsible for morphine-induced changes in the immune system being undefined. In addition, most of the heroin addicts are polydrug users. It is necessary to better understand the way in which heroin modulates immune responses, as well as the relationship between these effects, and to investigate whether this results in increased susceptibility to infections. We focused our attention on studies of the heroin-addicted and heroin withdrawal subjects by considering the lymphocyte proliferative responses, the expression of total T lymphocytes (CD3), T-helper cells (CD4), cytotoxic T-cell (CD8) antigenic markers of T-cells, B cells and NK cells. We conducted studies in humans because humans are significantly different from even the closest primates, and certainly profoundly different from rodents, with respect to certain specific immune indices and the pharmacokinetics of many drugs, as well as neuroendocrine functions. This is the first study of the immune function in heroin withdrawal subjects who used the “cold turkey” method, with no supplement of methadone or other drugs in the withdrawal period.