Dermo‐epidermal Blister Formation by Linear IgA Dermatosis Sera in Normal Human Skin in Organ Culture

Fresh normal human skin samples were cultured at 37°C for 48 hours with sera from 3 patients with linear IgA dermatosis and 2 patients with dermatitis herpetiformis (DH). Dermo-epidermal separation (DES) occurred in the skin samples cultured with the sera from linear IgA dermatosis patients, and linear IgA deposition was observed in the dermo-epidermal junction zone. However, no IgA deposition or DES was observed in the skin cultured with the sera of DH patients or normal individuals. The results were the same when sera of patients with linear IgA dermatosis were heated at 56°C for 30 minutes before culturing with skin samples, but DES was prevented when a proteinase inhibitor, aprotinin (50%), or α2-macroglobulin (10 mg/dl) was added to the cultures. Our results suggest that IgA deposition in the basement membrane and proteinases are involved in the formation of vesicles in patients with linear IgA dermatosis, but complements are not directly involved.