Quantitative detection of epidermal growth factor and interleukin-8 in whole saliva of healthy individuals

• We propose a methodology for quantitative detection of biomarkers in whole saliva.
• Pretreatment of saliva with SDS increases the detection levels for EGF and IL-8.
• Secretion rate has a great impact on the output values of salivary biomarkers.
• Saliva sampling after meal intake gives reduced outcome for salivary biomarkers.

ObjectivesThis study aims to create consensus concerning the use of a methodology by which the handling of saliva is standardized and quantitative detection of IL-8 and EGF in whole saliva is achieved. Our study involves evaluating the extent to which the pre-treatment of saliva samples with an anionic detergent – sodium dodecyl sulphate (SDS) – improved detection levels for IL-8 and EGF.MethodsWhole saliva samples (n = 28) were collected from healthy individuals and a protease inhibitor cocktail was added immediately. They were treated with either SDS or PBS for 20 min and were then applied to a sandwich ELISA.Results and conclusionsSaliva is a complex viscous fluid that requires degrading before the analysis of salivary biomarkers. We found that pre-treatment of samples with SDS significantly increased the detection levels for both EGF (293%) and IL-8 (346%) when compared with PBS-treated pairs (⁎⁎⁎P < 0.001). According to the results we recommend: (i) pre-treatment of whole saliva samples with SDS for quantitative analysis (ii) using secretory output instead of concentration in the presentation of results to avoid individual variations and (iii) taking into consideration gender, age and meal intake since these have an impact on the secretory output of salivary proteins.