Quantification of secretory leukocyte protease inhibitor (SLPI) in oral gargle specimens collected using mouthwash.

BACKGROUND: Secretory leukocyte protease inhibitor (SLPI) is an innate immunity-associated protein known to inhibit HIV transmission, and is thought to inhibit a variety of infectious agents, including human papillomaviruses (HPVs). We aimed to optimize an established ELISA-based SLPI quantification assay for use with oral gargle specimens collected using mouthwash, and to assess preliminary associations with age, smoking status, and alcohol intake. METHODS: Oral gargle supernatants from 50 individuals were used to optimize the Human SLPI Quantikine ELISA Kit. Sample suitability was assessed and quality control analyses were conducted. RESULTS: Salivary SLPI was successfully recovered from oral gargles with low intra-assay and high inter-individual variability. Initial measurements showed that salivary SLPI varied considerably across individuals, and that SLPI was inversely associated with age. CONCLUSIONS: This optimized assay can be used to examine the role of SLPI in the acquisition of oral HPV and other infections.