Utility of multiple sampling in reducing variation of salivary interleukin-8 and interleukin-1β mRNA levels in healthy adults.

BACKGROUND Salivary mRNA biomarkers can exhibit significant variation over time. The purpose of this study was to investigate the pattern and magnitude of variation of salivary mRNA biomarkers and to explore the effect of performing replicate assays and multiple sampling on the dispersion of salivary biomarkers. METHODS Salivary interleukin-8 (IL-8) and interleukin-1β (IL-1β) mRNAs, developed as biomarkers for oral cancer detection, were selected and measured from 15 healthy subjects at 4 different time points on the same day. RESULTS Salivary IL-8 and IL-1β mRNA levels fluctuated randomly over time without predictable rhythm and showed higher within-subject biological variation than analytical variation. The dispersion of salivary IL-8 and IL-1β mRNAs was more effectively reduced by taking multiple saliva sample measurements than by performing replicative assays. CONCLUSION Taking multiple saliva samples can effectively reduce variation of salivary IL-8 and IL-1β mRNA levels in healthy adults.