Adjuvant Effects on Morphine-Induced Suppression of Immune Responses to MN rgp120/HIV-1 in Mice

Abstract

Intravenous drug users (IDUs) are more susceptible to infections, including HIV-1 (1Haverkos and Lange, 1990), and have been shown to have suppressed immune responses (Brown et al., 1974). This may be due to a combination of effects, including immunosuppressive effects of the drugs themselves (i.e., morphine, heroin, cocaine), poor nutrition and sharing contaminated needles. Given that a very high percentage of heroin users report injection, often with shared equipment, as the primary route of administration, this population is at high risk for becoming infected with HIV-1. We have shown previously that morphine decreases primary and secondary antibody responses both in vitro and in vivo (Bussiere et al.,1993b) in a murine model. This model may provide information on one risk factor; the interaction between the drugs of abuse and immune responses to a subunit vaccine, recombinant glycoprotein 120 from the MN strain of HIV-1 (rgp120). In addition, morphine has been shown to promote the growth of HIV-1 in vitro (Peterson et al.,1990; Squinto et al.,1990), and promote the growth of SIV in vitro and in vivo in macaques (Chuang et al.,1993). Thus, these drugs may also influence the infectivity of the virus.