Effects of cocaine and morphine on IgG production by human peripheral blood lymphocytes in vitro

Elevated serum levels of IgG are amongst the immunological abnormalities exhibited by intravenous drug addicts. We therefore addressed the hypothesis that cocaine and morphine (the major metabolite of heroin) exert a direct effect on human B cell function in vitro. Human peripheral blood mononuclear cells from normal individuals were incubated for 7 days with the T cell-dependent B cell activator pokeweed mitogen (PWM) and serial dilutions of either cocaine or morphine. At the end of this time total IgG was measured by use of a sandwich ELISA incorporating a biotin-labelled affinity-purified anti-IgG and streptavidin peroxidase. At concentrations relevant to those found in plasma, morphine and cocaine did not affect PWM-stimulated IgG synthesis in vitro. We suggest that these drugs of abuse do not directly influence human B cells, but in vivo exert immune modulatory effects via indirect mechanisms.