Children with untreated food allergy express a relative increment in the density of duodenal gamma delta(+) T cells

Background: We investigated whether children with food allergy (FA) express increased densities of intraepithelial gamma delta (+) T cells similarly t o subjects with celiac disease. Methods: The duodenal specimens taken by ga stroduodenoscopy from 20 children with untreated FA, 17 with treated FA, 12 with celiac disease (CD) and 12 controls were studied with monoclonal anti bodies and a three-layer peroxidase staining method. Results: The subjects with untreated FA expressed equal densities of total intraepithelial CD3(+) and alpha/beta (+) T cells, but significantly higher densities of gamma de lta (+) cells than the subjects currently on an elimination diet for FA or the controls. Accordingly, their gamma delta (+)/CD3(+) ratio was higher. O n the other hand, the results differed clearly from CD, where all the three cell populations showed high densities. Another finding that discriminated the subjects with FA from the CD patients was endoscopic examination. Lymp honodular hyperplasia (LNH) of the duodenal bulb with a normal villous patt ern was demonstrated in 14 (70%) of the 20 subjects with untreated FA and i n 8 (47%) of the 17 with treated FA, but in none of the celiac patients or controls. Surprisingly, the biopsy samples from the subjects with FA showed quite normal histological findings. Conclusions: According to this prelimi nary observation, high densities of intraepithelial y delta (+) T cells and a significantly elevated gamma delta (+)/CD3(+) ratio are associated with untreated FA. If seen LNH in a gastroduodenoscopy and/or increased densitie s of gamma delta (+) T cells in the biopsy specimen, the possibility of gas trointestinal FA should be reliably assessed by a food challenge.