Failure of intradermal skin testing with gluten to produce delayed hypersensitivity reactions in patients with dermatitis herpetiformis.

Summary Dermatitis herpetiformis (DH) is characterized by a rash and a gluten-sensitive enteropathy (GSE) indistinguishable from that of coeliac disease. T-cell-mediated mechanisms have been implicated in the pathogenesis of GSE. It seems feasible that intradermal injection of gluten, in patients known to have GSE, could lead to an influx of T cells sensitized to gluten, with subsequent development of a delayed hypersensitivity-type reaction. Six patients with DH and three normal subjects had intradermal injections of‘Frazer's fraction III’ (FFIII; the partial peptic tryptic digest of gluten which is known to be antigenic) and phosphate-buffered saline (PBS) as a control. Skin biopsies were taken at PBS and FFIII injection sites at 48 h. In addition, two of the patients with DH had biopsies taken of FFIII injection sites at 6 h. Monoclonal antibodies and the avidin-biotin-peroxidase technique were used to stain for T cells in the skin biopsies. A monoclonal antibody to a neoepitope exposed in the terminal complement complex and an immunofluorescent method were used to detect the presence of terminal complement component in biopsies taken from two of the control subjects and two of the patients. Both patients and control subjects developed a weal and flare within a few minutes of injecting the FFIII, and this persisted for up to 6 h. No skin reaction was present in either the patients or the control subjects at 48 h. No skin reaction was visible at any time following injection of PBS. There was no increase in T cells in biopsies taken at 6 or 48 h from the FFIII injection sites compared with the PBS injection sites. Terminal complement component was present in the biopsies taken from DH patients at both the PBS and FFIII injection sites (6 and 48 h), but was absent from the biopsies taken from the control subjects. Normal delayed hypersensitivity responses to a battery of common recall antigens showed that the lack of response to FFIII was antigen specific. Thus, this study suggests that the T cells sensitized to gluten in patients with GSE are unable to migrate to the skin.