Iodine and gliadin challenge on oral mucosa in dermatitis herpetiformis

Oral lesions and mucosal inflammatory changes may appear in dermatitis herpetiformis (DH). We examined whether potassium iodine, known to initiate blisters in the DH skin, or wheat gliadin, responsible for T-cell-dependent intestinal damage, can induce visible or microscopic changes in oral mucosa. Six patients with active DH were challenged with crude gliadin and 50% potassium iodine applied in patch test chambers on buccal mucosa for 12 h. After reading, biopsies were taken from the challenged and non-challenged mucosa. No macroscopic or microscopic vesicles were seen. However, gliadin- but not iodine-challenged epithelium showed increased numbers of CD4+ lymphocytes in all 5 patients with representative specimens (p = 0.06). No marked changes were found in the numbers of CD8+ or TcR alpha/beta+ lymphocytes, and the numbers of TcR gamma/delta+ cells remained at a low level. The results show that oral mucosa is resistant to production of macroscopic or microscopic DH lesions. It is, however, capable of reacting to locally applied gliadin by a T-cell response consisting of CD4+ lymphocytes.