Quantification of human myeloperoxidase in oral fluids

Peroxidase activity in human whole saliva is derived from salivary peroxidase and myeloperoxidase. Present spectrophotometric assays are relatively nonspecific and influenced by ions present in salivary secretions, resulting in an over and/or underestimation of peroxidase activities. Specific polyclonal or monoclonal antibodies would greatly simplify the identification of salivary peroxidase and myeloperoxidase in human saliva and determine the relative contribution of each enzyme to the total peroxidase activity in human saliva. In the present study, a highly purified preparation of myeloperoxidase was used to raise polyclonal antibodies against the antigen. The antibodies were purified and extensively characterized in terms of their ability to interact with the antigen, with other mammalian peroxidases, and with other proteins present in salivary fluids. The antibodies recognized only myeloperoxidase and did not cross-react with any of the substances tested, showing that these antibodies can be used to detect and differentiate myeloperoxidase from other peroxidases in saliva. We have also developed and tested a sandwich ELISA which can be used in a clinical setting to quantify myeloperoxidase in whole saliva and gingival crevicular fluid.