The pathogenic mechanisms of blister formation in bullous pemphigoid.

Normal human skin was cultured with sera, IgG fractions, and blister fluids (BF) from patients with bullous pemphigoid. Antibody binding (IgG) was observed by immunofluorescence techniques at the dermal-epidermal junction of all skin explants culture with sera, IgG fractions, and BF. Dermal-epidermal separation was observed only in the skin explants cultured with BF. Dermal-epidermal separation was observed in 19 out of 20 explants cultured with BF obtained from fresh bullae. In addition, dermal-epidermal separation can be produced in vivo 6 hr after the injection of BF into the dorsal skin of Hartley guinea pigs. Dermal-epidermal separation was not observed in skin explants cultured with heat-inactivated (56 degrees, C 30 min) BF, although antibody binding was observed. In addition, dermal-epidermal separation did not occur when the BF were preincubated with rabbit antihuman C1, C3, C4, and C5 antibodies. These observations suggested that both antibody and complement were essential for the production of dermal-epidermal separation. Since patient sera failed to produce dermal-epidermal separation, other factor(s) present in BF but absent from serum might be necessary for the production of dermal-epidermal separation. The addition of the proteinase inhibitors, pepstatin, EDTA, and soy bean trypsin inhibitor, did not inhibit the formation of dermal-epidermal separation. In contrast, the presence of alpha 2-macroglobulin inhibited dermal-epidermal separation.