Correlates of Mucosal Immunity and Upper Respiratory Tract Infections in Girls

In this study we examined whether salivary hormones, physical activity and adiposity were correlated with secretory immunoglobulin A (sIgA) and frequency of upper respiratory tract infections (URTI) in 43 early-pubertal and 59 late-pubertal girls. Physical activity was measured using accelerometers and relative body fat was assessed using bioelectrical impendence. Resting saliva samples were obtained between 1500 and 1800 hr and assayed for sIgA, cortisol and testosterone. Participants completed a one-month health log to record URTI frequency. Early-pubertal girls were more physically active, had less adiposity, but lower concentrations of sIgA than late-pubertal adolescents (122.7 +/- 91.6 vs 201.9 +/- 102.9 pg/ml, respectively). The frequency of URTI was similar in the two groups. Neither sIgA nor URTI were correlated with salivary hormones, physical activity or adiposity within the early-pubertal girls. In the late-pubertal group, sIgA was negatively associated (r = -0.44; p < 0.05) with cortisol, and positively associated (r = 0.41; p < 0.05) with the testosterone to cortisol ratio. These results suggest that mucosal immunity increases with pubertal maturation, while higher cortisol is associated with lower mucosal immunity in adolescents.