Identification of SLPI (secretory leukocyte protease inhibitor) in human mast cells using immunohistochemistry and in situ hybridisation.

Recently interest has been focused on secretory leucocyte protease inhibitor (SLPI) and its role in immediate hypersensitive reactions, possibly by inhibiting mast cell chymase. The purpose of this investigation was to show whether or not SLPI is produced in mast cells. Double-immunolabelling revealed that SLPI coexists with mast cell tryptase (60%) and chymase (37%). On the other hand, in situ hybridisation studies demonstrated the expression of SLPI mRNA in all mast cells. The differences in results can be attributed to the fact that in situ hybridisation is a more sensitive method than immunohistochemistry. Hence, we conclude that SLPI is produced in human tonsillar mast cells.

Distribution of the secretory leucocyte proteinase inhibitor in human articular cartilage.

The secretory leucocyte protease inhibitor, SLPI, is a low molecular weight inhibitor of proteases such as elastase and cathepsin G, which are released from leucocytes during phagocytosis. The purpose of this study was to show whether or not SLPI is produced in articular chondrocytes. In articular disorders, the protease-antiprotease balance is disturbed. For this reason it would be interesting to establish the source of SLPI. The presence of SLPI was demonstrated using immunohistochemistry and in situ hybridization, hence we conclude that SLPI is produced in the chondrocytes of human articular cartilage.

Production and secretion of pancreatic secretory trypsin inhibitor in normal human small intestine.

The aim of this study was to prove the production and secretion of pancreatic secretory trypsin inhibitor (PSTI) in human small intestine. To achieve this we analyzed the content of immunoreactive PSTI (irPSTI) in rinsing fluid from isolated small intestine, using the urea method to estimate the volume of epithelial lining fluid recovered. IrPSTI, measured by an enzyme-linked, immunosorbent assay (ELISA), was present in both free and complexed form. The free PSTI showed intact biologic activity, binding trypsin in stable complexes. The complexed PSTI was dissociated on acidification. With the reverse transcriptase polymerase chain reaction (RT-PCR) and Southern blot hybridization, PSTI mRNA was demonstrated in the mucosa of the ileum. These findings indicate that PSTI is produced and secreted in the small intestinal epithelium and may be part of defence system in intestinal mucosa.

Localization of immunoreactive secretory leukocyte protease inhibitor (SLPI) in intestinal mucosa.

Secretory leukocyte protease inhibitor (SLPI) is the dominant protease inhibitor in the mucus secretions of the repiratory and genital tracts, and local production seems likely, as immunoreactive SLPI has been found in the corresponding mucosa. To our knowledge, SLPI has not been previously demonstrated in intestinal epithelia or secretions. In an earlier study, however, we found surprisingly high levels of SLPI in peritonitis exudate from patients with gastrointestinal perforations. This study extends these observations by demonstrating the presence of immunoreactive SLPI in intestinal mucosa. In the small intestine, SLPI was present in Paneth cells and in scattered mucosa cells of goblet-type. In normal mucosa of the large bowel, SLPI was also found in scattered cells of goblet-type in the epithelium. In addition, immunoreactive SLPI was frequently found in colonic adenomas. The findings in this study raise several interesting questions on the possible role of SLPI in the gut epithelial defense against inflammatory assaults.

Localisation of secretory leucocyte proteinase inhibitor mRNA in nasal mucosa.

Human secretory leucocyte proteinase inhibitor (SLPI) is a low-molecular weight, acid-stable inhibitor of polymorph-nuclear granulocyte elastase and cathepsin G. Previous reports have demonstrated the existence of SLPI in the respiratory tract, salivary glands and cervical mucosa. Positive staining for SLPI using immunohistochemical techniques has been reported in serous glands in nasal mucosa. We now confirm this observation and show, using in situ hybridization, that the pattern of expression of mRNA corresponds to the distribution of the encoded protein, SLPI. This, together with the high concentration of SLPI in nasal secretions, confirms the hypothesis of a local production of SLPI in the mucous membranes.

Immunocytochemical distribution of trypsinogen and pancreatic secretory trypsin inhibitor in normal and neoplastic tissues in man.

Immunoreactive trypsinogen and pancreatic secretory trypsin inhibitor (PSTI) were demonstrated in pancreas by means of an immunoperoxidase technique. They had the same distribution in acinar cells of 'normal' human exocrine pancreas tissues. Ductal adenocarcinoma tissue and pancreatic undifferentiated carcinoma contained neither antigen. Scattered 'normal'-looking cells in the border area between normal and neoplastic tissue of both types of tumor stained positively for trypsinogen and for PSTI.

Localization of antileukoprotease in the parotid and the submandibular salivary glands.

Antileukoprotease is the dominating inhibitor of granulocyte elastase and cathepsin G in normal human mixed and parotid saliva. The distribution of antileukoprotease in the submandibular and parotid glands was analysed with an immunoperoxidase technique using specific antibodies against antileukoprotease. Antileukoprotease was demonstrated in the serous cells of both the submandibular and parotid glands. These findings suggest that there is a local production of the inhibitor in the parotid gland and submandibular gland and are in agreement with our previous work which demonstrated high concentrations of the inhibitor in parotid saliva.

Distribution of antileukoprotease in upper respiratory mucosa.

Human respiratory tract secretions contain enzyme inhibitors derived from plasma and a low molecular weight, acid-stable protease inhibitor, antileukoprotease. The distribution of antileukoprotease in normal upper respiratory tract mucosa has been studied using an immunohistologic technique. The inhibitor was localized to the serous parts of the submucosal glands of the maxillary sinus and the trachea but was not demonstrable in mucous glands and goblet cells. It is concluded that the antileukoprotease found in respiratory tract secretions is produced locally in the submucosal serous glands.

Glutaminyl-peptide gamma-glutamyltransferase dependence of the uptake of trypsin-alpha-macroglobulin complexes by macrophages.

The canine alpha-macroglobulin 125I-trypsin complexes were prepared and exposed to canine alveolar macrophages. The binding of the complexes to cells was time- and dose-dependent. A rapid uptake and degradation of the bound complexes was evidenced by the finding of less than 20% cell-bound radioactivity after a 4 h incubation at 20 degrees C. The canine alveolar macrophages contain a glutaminyl-peptide gamma-glutamyltransferase which shows slightly retarded agarose gel electrophoretic mobility as compared to the respective enzymes from tissues of other species, such as guinea pig and man. Evidence is presented that the binding and degradation of trypsin alpha-macroglobulin complexes by macrophages is dependent on this gamma-glutamyltransferase. Monodansylthiacadaverine, a strong inhibitor of this enzyme, blocks the binding of trypsin-alpha-macroglobulin complexes to macrophages and (probably as a consequence of this) degradation of the complexes. Furthermore, this gamma-glutamyltransferase is a calcium-dependent enzyme and the process of binding trypsin-alpha-macroglobulin complexes to the macrophages was likewise found to be calcium-dependent.