METHODS: We assessed specific IgG4 to milk proteins (alpha-lactalbumin, beta-lactoglobulin, and caseins) in sera from 71 children with EoE. Boys and girls were compared, with sub-stratification into younger (2-9 years) and older (10-18 years) groups.
RESULTS: In the cohort there were 54 boys (19 younger, 29 older) and 19 girls (8 younger, 15 older). Younger boys had lower levels of IgG4 to all three milk proteins as compared to older boys. For beta-lactoglobulin this was highly significant (p=0.002). In contrast younger girls trended towards higher levels than older girls, but the association did not reach statistical significance. Although overall there was no significant difference in IgG4 levels between boys and girls, the younger boys did have lower levels of IgG4 than younger girls.
CONCLUSIONS: EoE is more prevalent amongst boys, a distinction that holds true both before and after puberty. The reason for this bias is not yet known. We show here that there are differences in the IgG4 response to milk proteins in children with EoE when stratified by sex and age. Interestingly older boys have stronger responses than younger boys, but this trends towards the opposite amongst girls. This raises the question of whether differences in milk-specific IgG4 could be relevant to the sex-bias in the development of EoE.