We studied the relationship between cAMP and house dust mite-induced cytokine production in T cells from mite-sensitive patients with atopic dermatitis. T cells from atopic dermatitis patients secreted high level of interleukin-13 (mean 851.1 pg per ml) when cultured with autologous monocytes pulsed with Dermatophagoides pteronyssinus extract. Dermato- phagoides pteronyssinus-induced interleukin-13 secretion was not detected in normal subjects. Adenylate cyclase inhibitor MDL 12,330A and cyclic nucleotide phosphodiesterase type 4 inhibitor rolipram blocked Dermatophagoides pteronyssinus-induced interleukin-13 secretion in atopic dermatitis T cells. In atopic dermatitis T cells, cAMP level rose at 5 min after Dermatophagoides pteronyssinus stimulus then decreased to the basal level at 1 h. MDL 12,330A blocked the Dermatophagoides pteronyssinus-induced cAMP elevation while rolipram blocked its reversal. In atopic dermatitis T cells, adenylate cyclase activity increased at 5 min after Dermatophagoides pteronyssinus stimulus, followed by the increase of cyclic nucleotide phosphodiesterase activity at 15 min. In atopic dermatitis T cells, phospholipase C inhibitor ET-18-OCH3 blocked Dermatophagoides pteronyssinus-induced activation of adenylate cyclase, while rolipram, protein kinase A inhibitor H-89, and MDL 12,330A blocked the activation of cyclic nucleotide phosphodiesterase. These results suggest that Dermatophagoides pteronyssinus may first increase cAMP in atopic dermatitis T cells by activating adenylate cyclase via phospholipase C, and next decrease cAMP by activating cyclic nucleotide phosphodiesterase 4 via protein kinase A, which may be activated by adenylate cyclase-generated cAMP signal. These events are required for interleukin-13 response Dermatophagoides pteronyssinus.