Background: Both endotoxin exposure and a single nucleotide polymorphism in one of its receptors, CD14 C-260T, have been separately associated with total serum IgE levels. Furred pets might also influence IgE levels through their effects on endotoxin levels. However, how these factors interact to influence total IgE levels is not well known, especially in adults.
Objective: We sought to investigate the interactive relationship between endotoxin levels, pet exposure, and CD14 C-260T genotype on total serum IgE levels in adults.
Methods: Mothers enrolled in an ongoing cohort study were genotyped for the CD14 C-260T polymorphism. Exposure to pets was assessed by using questionnaires and dust allergen levels collected in the home. Endotoxin exposure was estimated by using dust collected from mothers' bedroom floors. The primary outcome measure was total serum IgE level.
Results: CD14 C-260T genotype was assessed in 517 (85.2%) of the 607 women enrolled in the study. The CD14 C-260T genotype was significantly associated with total IgE levels; however, this relationship appeared to be modified by the level of endotoxin exposure. Similar interactions between CD14 C-260T and pet exposure were not seen, regardless of the measure of pet exposure used.
Conclusions: The CD14 C-260T genotype and endotoxin exposure together appear to influence total serum IgE levels in adults. The absence of a similar gene-environment interaction for pet exposure suggests separate mechanisms of action.
Clinical implications: A common polymorphism in the endotoxin receptor, CD14 C-260T, and dust endotoxin levels in the home might interact to influence total serum IgE levels into adulthood.