INCREASE OF BRADYKININ-STIMULATED ARACHIDONIC-ACID RELEASE IN A DELTA-F508 CYSTIC-FIBROSIS EPITHELIAL-CELL LINE

Modification of chloride conductance by bradykinin in epithelial cells has been attributed to an activation of protein kinase A resulting fr om adenylcyclase stimulation by arachidonic acid cyclooxygenase produc ts. The results presented here compare tracheal epithelial cell lines from one control and two cystic fibrosis patients which were immortali zed by transfection with the SV40 large T oncogene. The three cell lin es presented the same arachidonic acid content, turnover and mobilisat ion under basal conditions. Bradykinin stimulated the release of arach idonic acid and the synthesis of cyclooxygenase derivatives (mainly PG E2). The cell line from the cystic fibrosis patient bearing a phenylal anine 508 deletion, which is the major form of the disease, showed a h igher bradykinin-induced arachidonic acid release than either control cells or cells from a patient presenting a minor form of the disease. This higher sensitivity suggests a dysregulation of phospholipase A2 s timulation in cystic fibrosis cells and was confirmed on non-immortali zed tracheal epithelial cells in primary culture and on skin fibroblas ts from patients bearing the same mutation. This defect is associated with a potentiation of cholera toxin pretreatment on cAMP content of D ELTAF508 cell line. The impaired control of arachidonic acid release c annot be attributed to an increased number of bradykinin binding sites , since this increase was similar in the two cystic fibrosis cell line s.