The effects of
cocaine, its metabolites, and other
alkaloids from Erythroxylon coca on the primary immune responses of ICR mice to sheep red blood cells (sRBC) and
dinitrofluorobenzene (
DNFB) were studied. The Jerne hemolytic plaque assay (PFC) was used to evaluate the humoral immune response to sheep red blood cells, and the delayed type
hypersensitivity (DTH) response to
DNFB was used to study cellular immune responsiveness. Drugs were given in single daily po doses for 5 consecutive days beginning on the day of immunization or 3 days prior to and on Days 3 and 4 after immunization. Inhibition of both PFC and DTH responses occurred at doses of 15 to 60 mg/kg of
cocaine and was greatest when fed during immunization. Five other
alkaloids also suppressed the PFC and/or DTH response.
Cocaine was more suppressive than the six other
alkaloids tested.
Ethanol (5 g/kg) did not suppress the DTH response and only marginally suppressed the PFC response. delta 9-THC inhibited the PFC response at doses of 10 mg/kg and marginally suppressed the DTH response at doses of 30 mg/kg, but not at other doses ranging from 10 to 90 mg/kg. Coadministration of 5 g/kg
ethanol and 15 mg/kg
cocaine resulted in 50% antagonism of effects of
cocaine on the PFC response and complete antagonism of the suppression of the DTH response, but only if these substances were given during the period of immunization. Like
ethanol, delta 9-THC also abolished the inhibitory effects of
cocaine on the PFC and DTH response but only if coadministered during the period of immunization. Coadministration of
ethanol and delta 9-THC resulted in synergistic inhibition of both DTH and PFC responses.