Beta-glucan exposure and allergic disease in infancy

Background:

Early life exposure to microbial agents may protect against the development of allergic disease in infancy. This study assessed whether exposure to beta-glucan (a fungal biomass marker) at age 3 months was associated with allergic disease and asthma symptoms in infancy.

Methods:

Living room floor dust was collected at age 3 months and analysed for beta-glucan by a modified Limulus amoebocyte lysate method. Skin prick tests to indoor allergens were performed on 546 infants at age 15 months for whom dust was available for analysis and asthma symptoms were collected by questionnaire then and at age 2, 3 and 4 years. Adjusted odds ratios (aOR) for the association of beta-glucan with allergic disease and asthma symptoms were determined by logistic regression. Adjusted geometric mean ratios were used to show determinants of beta-glucan.

Results:

The concentration of beta-glucan at the 3rd tertile was significantly associated with skin prick test positivity, aOR: 1.88 (95% CI: 1.17-3.03; p = 0.0097), but not with wheeze or other asthma symptoms at age 15 months, 2, 3 or 4 years. Beta-glucan levels were higher in spring compared to summer, geometric mean ratios were: 1.22 (95% CI: 1.01-1.48; p = 0.04) and 1.25 (95% CI: 1.09-1.44; p = 0.001) respectively for ng/m2 and ng/g. Beta-glucan levels expressed as ng/g were slightly higher in Christchurch than in Wellington, geometric mean ratio: 1.11 (95% CI: 0.99-1.21; p = 0.06). No significant differences in beta-glucan levels were found between living room floors with carpets/rugs and those with bare floors.

Conclusion:

Early life exposure to beta-glucan may lead to allergic sensitisation in infancy.