Predictors of interleukin-1β and interleukin-1 receptor antagonist in infant saliva

Objectives This study assesses the feasibility of measuring interleukin-1 beta (IL-1 beta) and interleukin-1 receptor antagonist (IL-1ra) in infant salivary samples as representative of pro- and anti-inflammatory processes, and explores predictors of these biomarkers in a US population. Methods Data were collected from 73 US mother-infant pairs. Salivary samples were collected with an infant swab and analyzed for IL-1 beta, IL-1ra, and immunoglobulin A (IgA) using ELISA. Household, maternal, infant, and anthropometric predictors were selected using stepwise regression to build final multivariate models. Results Both IL-1 beta and IL-1ra can be feasibly measured in infant saliva. The predictors in the final IL-1 beta model were IL-1ra and reported infant illness. IL-1 beta, IgA, infant age, household income, maternal BMI, and infant weight-for-agez-score were significant in the final model for IL-1ra. Conclusions IL-1 beta and IL-ra are useful biomarkers of immune function for infants. In particular, IL-1ra has the potential to address the relationship between immune function and body composition in the mother-infant dyad.