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Salivary myeloperoxidase of young adult humans
Abstract:
Leukocytes, principally polymorphonuclear leukocytes (PMNs), enter the oral cavity where they release a portion of their constituents, including myeloperoxidase, into oral fluids. A greater number of PMNs in the oral cavity are associated with oral inflammation. However, the quantitative contribution of the PMN to oral fluids, including saliva, during various conditions is poorly understood. An assay method based on the adsorbance loss at 278 nm from the reaction of the myeloperoxidase product hypochlorous acid with monochlorodimedon to yield dichlorodimedon was developed for the quantitation of salivary myeloperoxidase. Myeloperoxidase was determined in supernatants of whole saliva obtained at low and moderate flow rates and in parotid saliva collected during moderate and pronounced stimulation from young adults with minimal oral inflammation. The greatest myeloperoxidase activity was in whole saliva supernatants collected at low flow rates where PMN products have an opportunity to accumulate. Lesser quantities of myeloperoxidase were found in both the whole saliva supernatants and parotid saliva obtained at the faster flow rates. Low flow rate whole saliva supernatants contained about 25% of the myeloperoxidase in the PMNs which enter the oral cavity. Myeloperoxidase is responsible for a significant portion (15-20%) of the total peroxidase activity in supernatants of whole saliva obtained at low flow rates. Preliminary results indicate that young adults with phenytoin-associated gingival overgrowth or who smoke have more myeloperoxidase activity in low flow rate whole saliva.
Insights
Salivary myeloperoxidase (MPO) levels, indicative of polymorphonuclear leukocytes (PMNs), are highest in low-flow saliva. This finding helps quantify oral inflammation and may aid in diagnosing conditions like gingival overgrowth.
Area of Science:
- Oral Biology
- Biochemistry
- Immunology
Background:
- Leukocytes, particularly polymorphonuclear leukocytes (PMNs), infiltrate the oral cavity, releasing constituents like myeloperoxidase (MPO) into oral fluids.
- Elevated PMN presence correlates with oral inflammation, but their quantitative contribution to oral fluids, including saliva, remains unclear.
Purpose of the Study:
- To develop and apply an assay for quantifying salivary myeloperoxidase (MPO) to understand its contribution to oral fluids under various conditions.
- To investigate MPO levels in whole and parotid saliva at different flow rates in young adults with minimal oral inflammation.
Main Methods:
- Developed a spectrophotometric assay measuring absorbance loss at 278 nm, based on the reaction of MPO product hypochlorous acid with monochlorodimedon.
- Quantified MPO in whole saliva from low and moderate flow rates and parotid saliva during moderate and pronounced stimulation.
- Collected saliva samples from young adults with minimal oral inflammation.
Main Results:
- The highest MPO activity was observed in whole saliva supernatants collected at low flow rates, allowing for PMN product accumulation.
- Lower MPO quantities were detected in whole and parotid saliva obtained at faster flow rates.
- Low-flow whole saliva contained approximately 25% of the MPO found in infiltrating oral cavity PMNs and accounted for 15-20% of total salivary peroxidase activity.
Conclusions:
- Salivary MPO levels are significantly influenced by saliva flow rate, with higher concentrations found at low flow rates.
- The developed assay provides a method for quantifying salivary MPO, offering insights into oral inflammatory processes.
- Preliminary data suggest elevated MPO activity in low-flow saliva of individuals with phenytoin-associated gingival overgrowth or those who smoke.