Intestinal permeability as assessed with polyethyleneglycols in birch pollen allergic children undergoing oral immunotherapy.

Twenty-four children with rhinoconjunctivitis due to birch pollinosis were treated in a double-blind manner with enteric-coated capsules containing either a high dose of a birch pollen preparation (n = 11) or placebo (n = 13). The permeability of the small intestine was analysed at three different occasions with a mixture of differently sized polyethyleneglycols (PEG 400 and PEG 1000), before the start of oral immunotherapy (OIT), at the moment of maximum allergen dose, and after 3 months of therapy which was at the beginning of the pollen season. The actively treated children did not significantly change their permeability characteristics as determined from PEG recovery in the urine. By contrast, in the control group of patients the recovery of larger PEG molecules was decreased after 3 months of therapy, possibly due to the commencing pollen season. In addition, small bowel biopsies were taken at the time of maximum allergen dose from two children openly treated with OIT. Both specimens were normal.