A link has been found between reflux oesophagitis and allergy, thanks to research on eosinophilic oesophagitis published in the January issue of The Journal of Clinical Investigation. The condition, whose symptoms mimic gastro-oesophageal reflux, has shown an explosion in cases across the US in the few years since its discovery. It is distinguished from typical reflux in that it shows a characteristic infiltration of eosinophils in the gastrointestinal tract on biopsy. Dr Marc Rothenburg, Director of the Allergy and Clinical Immunology Section at the Children's Hospital Medical Center of Cincinnati, and the study's senior author, said, "There is a direct link between exposure to allergens that go to the lung — aeroallergens — and development of oesophageal inflammation." The new study has discovered that the pathway leading to eosinophilic oesophagitis is mediated by interleukin-5 (IL-5). The researchers gave an allergen that induces asthma to two sets of mice, which either had, or were deficient in, IL-5. All the mice with IL-5, but none of the deficient mice, developed oesophagitis. Dr Rothenburg commented, "two major pharmaceutical companies have an antibody in human trials that blocks IL-5. These drugs are being tried for asthma, but based on our findings I'd like to see IL-5 blockers tried in patients with eosinophilic oesophagitis." There is a significant subset of adult patients with reflux who do not respond to the available medications. Dr Rothenburg believes "a significant number of those may have an allergy-driven process; they have a different form of reflux that we're calling eosinophilic oesophagitis."