Immunostimulation and growth faltering in UK infants

The purpose of the study was to determine whether chronic immunostimulation could explain growth faltering in disadvantaged children in the UK, as it does in developing countries such as The Gambia. In all, 216 infants, age 10-21 months, were recruited when blood samples were taken for the routine or clinical purposes of a longitudinal study tracking a larger cohort of children. Aliquots of blood were collected on Guthrie cards to determine blood concentrations of albumin (Alb), alpha(1)-antichymotrypsin (ACT), and immunoglobulin G (IgG). Haemoglobin concentrations were determined by routine hospital laboratory analysis. Heights and weights were measured and converted to z-scores; birth weights were used with recruitment weight to calculate a 'thrive index' for each child. Age-corrected plasma IgG concentration was negatively associated with both height- and weight-for-age z-scores (P = 0.042 and 0.038, respectively) but not with the thrive index or body mass index z-scores. Blood haemoglobin levels were positively related to height- and weight-for age z-scores, as well as to the thrive index (P = 0.026, 0.014, and 0.007, respectively). Although significant, these relationships could only account for a small part the observed growth variation. Although the relationships were weak, the results suggest that some of the observed variation in growth of these UK infants may be explained on the basis of persistent immunostimulation or poor iron status. In terms of markers of immunostimulation (Alb, ACT, ACT:Alb ratio, IgG), both absolute levels and relationships with height-for-age are substantially different than those previously observed in cohort studies of infants in The Gambia.