Dermatitis herpetiformis: clinical and immunological aspects

Although many workers have demonstrated that the rash of dermatitis herpetiformis responds to withdrawal of gluten from the diet, there are many who remain sceptical. The role of a gluten free diet in the management of patients with dermatitis herpetiformis was re-examined and its beneficial effects confirmed. Furthermore, a gluten free diet was shown to protect patients with dermatitis herpetiformis from developing lymphoma but the diet had to be strict and the protective effect only became apparent once the diet had been adhered to for five years. Relatives of three patients (with a family history of dermatitis herpetiformis/coeliac disease) were screened in order to detect the clinical carrier rate for the genes for dermatitis herpetiformis and coeliac disease within these families. The carrier rate in the three families studied varied from 23% to 57%. This study demonstrated that many so-called "unaffected" relatives of patients with dermatitis herpetiformis may have silent or latent coeliac disease. Screening by means of serology alone was shown to be unreliable. The pathogenic mechanisms leading to the development of the rash and enteropathy are poorly understood. An infiltrate of T cells, composed mainly of activated CD4 positive memory cells, was shown to be present in the dermis of dermatitis herpetiformis lesional skin. Moreover, these T cells demonstrated over-representation of specific TCR Vβ subsets, namely Vβ2, Vβ5.2/5.3 and Vβ5.3. These findings would indicate that these T cells recognise a specific, but as yet unknown, antigen; the antigen is unlikely to be gluten because intradermal injection of Frazer's fraction III failed to elicit the rash of dermatitis herpetiformis in patients. An infiltrate of T cells is also found in the small intestinal mucosa of patients with dermatitis herpetiformis and coeliac disease. It has been proposed that these T cells belong predominantly to the TH1 group of cells and it has been suggested that IFN-γ, which is produced by these cells, plays a key role in the production of the small intestinal pathology. However, this hypothesis has not been supported by others. Reverse transcriptase-polymerase chain reaction and immunostaining demonstrated no statistically significant differences in the detection of mRNA for IFN-γ and IL-2 or their proteins when biopsies from patients with dermatitis herpetiformis who had villous atrophy were compared with a control group of patients. Finally, possible mechanisms, whereby ingestion of gluten in susceptible individuals leads to the rash of dermatitis herpetiformis, are discussed