[Immunotropic activity of the cAMP phosphodiesterase inhibitors caffeine and theophylline]

On mice immunized with ram erythrocytes it was shown that caffeine and theophylline (15 to 240 mg/kg thrice at different time intervals with respect to the antigenic stimulus) possess identical immunotropic activity. High doses of methylxanthines injected a few days before immunization increased and being administered during immunization decreased the indices of humoral immunity. Low doses of the drugs stimulated immunity but only when administered at the time close to the antigenic stimulus application.