Lysergic acid diethylamide (LSD) directly alters immune function when immune cells are exposed to it in a laboratory setting. At a high concentration of 100 microM, LSD suppresses the proliferation of B-lymphocytes, reduces production of the cytokines IL-2, IL-4, and IL-6, and inhibits the induction of cytotoxic T-lymphocytes. In contrast, at lower concentrations between 0.0001 and 0.1 microM, LSD enhances both basal and IL-2-augmented natural killer (NK) cell activity. These differential effects suggest that LSD can directly influence components of the immune system at concentrations potentially reached in the human body.
Noribogaine, a metabolite of ibogaine, reduced the development of tolerance to morphine's pain-relieving effect in male Swiss-Webster mice. Tolerance was induced by implanting a 25 mg morphine pellet for 4 days or by injecting morphine (20 mg/kg) twice daily for 4 days. In pellet-implanted mice, 20 mg/kg of noribogaine attenuated tolerance, while lower doses had no effect. In mice receiving multiple injections, 20 and 40 mg/kg doses also attenuated tolerance. Since noribogaine worked at lower doses than ibogaine (which required 40–80 mg/kg in previous work), the authors suggest ibogaine's effect may depend on its conversion to the more active noribogaine.