A study on salivary proline-rich peptide P-C with special reference to the presence of salivary peptide P-C in the human respiratory tract

Abstract

In order to elucidate whether Salivary Protein C and salivary peptide P-C, originally isolated from human saliva were present in tissues other than those of the salivary glands or not, an indirect immunofluorescence technique using both antisera against salivary peptide P-C and Salivary Protein C was carried out on human salivary glands and the human respiratory tract. As salivary peptide P-C-like immunoreactivity was detected in the serous cells of salivary glands by previous immunohistochemical study, the human respiratory tract was closed as model tissue, since tracheal and bronchial glands in the human respiratory tract consist of mucous and serous cells. Furthermore, to check whether salivary peptide P-C is a fragment of Salivary Protein C or not, the same immunohistochemical study was undertaken on the serial sections of salivary glands and the respiratory tract. Salivary peptide P-C and Salivary Protein C-like immunoreactivities were present in the serous cells of human salivary glands and in tracheal and bronchial cells. Furthermore, the same serous cells were immunostained with antisera against salivary peptide P-C, with antisera against Salivary Protein C and with antisera against Salivary Protein C preabsorbed with salivary peptide P-C. In view of the fact that the full sequence of salivary peptide P-C is identical to the COOH terminal 44 amino acid residues of Salivary Protein C, it was suggested that the full sequence of Salivary Protein C was present in the serous cells of human salivary glands and in those of tracheal and bronchial glands and that salivary peptide P-C was a fragment of Salivary Protein C.(ABSTRACT TRUNCATED AT 250 WORDS)