Developmental profiles of mucosal immunity in pre-school children

Abstract

The development of a competent mucosal immune system in children occurs after birth in response to exposure to antigen. This study investigated the effect of attending pre-school on mucosal immunity. 37 children aged 3.5 to 5 years who attended pre-school were observed for a 10 month period. Demographic information was collected on previous childcare experiences, the home environment and clinical information relating to the child and the family. A daily illness log was kept for each child. Saliva samples were collected to measure mucosal immune status. A multivariate longitudinal analysis of the relation between immunoglobulins in saliva and age, gender, childcare experience, pre-school exposure, number of siblings, environmental tobacco smoke (ETS) exposure, atopy and hospitalisation was conducted. There was a positive association of higher salivary IgA levels with winter, with children being older than 4 years (p< 0.001), having attended childcare prior to commencing pre-school (p<0.05) and having been exposed to ETS at home (p<0.05). Lower IgA levels were associated with being atopic (p<0.05). Higher salivary IgG levels were associated with exposure to ETS (p<0.001) while lower levels were associated to having atopy. Higher salivary IgM levels were associated with previous childcare experience (p<0.01) whilst having been hospitalised was associated with lower salivary IgM levels (p<0.01). Lagged analyses demonstrated that immunological parameters were affected by the number of respiratory infections in the preceding 2 months. It is concluded that environmental factors have a profound effect on mucosal immune development in pre-school children, with the potential for significant clinical sequelae.