Theophylline suppresses the release of interleukin-4 by peripheral blood mononuclear cells

To elucidate the mechanism of the anti-inflammatory effect of theophylline, peripheral blood mononuclear cells (PBMCs) collected from patients with bronchial asthma who had a RAST score for Dermatophagoides farinae (Df) > = 3 were stimulated with Df antigen, and the interleukin-4 (IL-4) production by the stimulated PBMCs was determined in the presence and absence of theophylline. The stimulated IL-4 production in the PBMCs was significantly suppressed by simultaneous treatment with theophylline (8 microg/ml). Furthermore, the intracellular 3',5'-adenosine monophosphate (cAMP) level following stimulation with Df was significantly higher in PBMCs simultaneously treated with theophylline (8 microg/ml) than in nontreated controls. These results suggest that theophylline suppresses the IL-4 production in inflammatory cells by increasing the intracellular cAMP level; this effect may thus provide an additional basis for the benefit of theophylline in antiasthmatic therapy.