Defensin-I, an antimicrobial peptide present in the saliva of patients with oral diseases

OBJECTIVES AND DESIGN: A preceding paper has noted a detection of defensin-I (HNP-I), a peptide with antimicrobial and cytotoxic properties, in the saliva of patients with oral squamous cell carcinoma. The present study deals with the presence of HNP-I in the saliva of patients with various oral diseases. METHODS: Whole saliva samples were obtained from the patients. HNP- I in the saliva was isolated and purified by HPLC and the amino acid sequence of the peptide was determined. The molecular weight of HNP-I was measured by mass spectrometry. The concentration of HNP-I in saliva was determined by comparing the height of eluted HNP-I with that of a synthetic HNP-I standard. RESULTS: The concentrations of HNP-I in the saliva of patients with oral lichen planus (n = 5), leukoplakia (n = 4), and glossitis associated with iron deficiency (n = 4) were 8.3 ± 4.3 μg ml^-1, 13.2 ± 7.9 μg ml^-1, and 11.4 ± 4.9 μg ml^-1, (mean ± s.d.), respectively. These concentrations were significantly higher than those in healthy subjects (0.8 μg ml^-1) (P < 0.01). In contrast, salivary HNP-I concentrations in patients with glossodynia (n = 4) and oral discomfort (n = 4) were similar to those in healthy subjects. CONCLUSIONS: Since HNP-I is a non-specific defensive peptide present in neutrophils, it may play an important role in the protection against diseases such as oral lichen planus, leukoplakia, and glossitis associated with iron deficiency.