FAILURE OF INTRADERMAL SKIN TESTING WITH GLUTEN TO PRODUCE DELAYED-HYPERSENSITIVITY REACTIONS IN PATIENTS WITH DERMATITIS-HERPETIFORMIS

Dermatitis herpetiformis (DH) is characterized by a rash and a gluten- sensitive enteropathy (GSE) indistinguishable from that of coeliac dis ease. T-cell-mediated mechanisms have been implicated in the pathogene sis of GSE. It seems feasible that intradermal injection of gluten, in patients known to have GSE, could lead to an influx of T cells sensit ized to gluten, with subsequent development of a delayed hypersensitiv ity-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 ph osphate-buffered saline (PBS) as a control. Skin biopsies were taken a t PBS and FFIII injection sites at 48 h. In addition, two of the patie nts with DH had biopsies taken of FFIII injection sites at 6 h. Monocl onal antibodies and the avidin-biotin-peroxidase technique were used t o stain for T cells in the skin biopsies. A monoclonal antibody to a n eoepitope exposed in the terminal complement complex and an immunofluo rescent 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 a nd flare within a few minutes of injecting the FFIII, and this persist ed 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 t ime following inject-ion of PBS. There was no increase in T cells in b iopsies taken at 6 or 48 h from the FFIII injection sites compared wit h the PBS injection sites. Terminal complement component was present i n the biopsies taken from DH patients at both the PBS and FFIII inject ion sites (6 and 48 h), but; was absent from the biopsies taken from t he control subjects, Normal delayed hypersensitivity responses to a ba ttery of common recall antigens showed that the lack of response to FF III was antigen specific. Thus, this study suggests that the T cells s ensitized to gluten in patients with GSE are unable to migrate to the skin.