LOCALIZATION OF IMMUNOREACTIVE TISSUE KALLIKREIN IN HUMAN TRACHEA

Tissue kallikrein is the major kininogenase detected in bronchoalveola r lavage fluids from asthmatics and may play a particularly important role in kinin generation during asthma. The present study was undertak en to determine the source of tissue kallikrein in the human lower air ways. Specific antisera to human tissue kallikrein were used to locali ze this enzyme by immunocytochemistry in human trachea. Immunoreactive tissue kallikrein was localized in submucosal glands of the lamina pr opria but was not detected in epithelial cells or goblet cells. Specif ic staining for tissue kallikrein was not detected in all cells of the submucosal glands but was restricted to cells forming demilunes in th e distal portions of the glands. When consecutive serial sections of s ubmucosal glands were alternately stained using antiserum to tissue ka llikrein and a periodic acid Schiff stain (to detect mucus), it was re vealed that immunoreactive tissue kallikrein was present only in serou s cells and not in mucus cells. The localization of tissue kallikrein to the serous cells of submucosal glands should facilitate studies to regulate the release of this enzyme. Regulation of tissue kallikrein r elease may provide a mechanism to reduce kinin generation during asthm a.