Prolonged survival of experimental heart transplantation induced by theophylline

High levels of cyclic adenosine monophosphate (cAMP) in lymphocytes are associated with a reduction in many immunological functions. Theophylline, a drug effective in elevating lymphocyte cAMP levels, was employed as a single immunomodulator treatment in rats submitted to heterotopic heart allotransplantation. In 3 strain combinations, the graft survival was consistently prolonged in treated animals in comparison with untreated controls.