IntroductionBullous pemphigoid (BP) is an acquired autoimmune skin disease characterized by autoantibodies against two hemidesmosomal antigens, BP230 (BPAG1) and BP180 (BPAG2), and subepidermal blisters (1). These antihemidesmosomal autoantibodies can be detected, along with complement proteins, bound to the dermal-epidermal junction (DEJ) of perilesional skin. In the skin lesions of these patients, basal keratinocytes detach from the underlying dermis at the level of the lamina lucida, leading to subepidermal blistering (1, 2). Eosinophils (3, 4), neutrophils (5), lymphocytes (6), monocyte/macrophages (7,8), and mast cells (MCs; 7, 9) are present in the upper dermis of lesional areas in patients with BP. Interestingly, MC degranulation is a feature of BP (7, 9). Chemoattractants from MCs, including eosinophilic/neutrophilic chemotactic factors and histamine, are present at high concentrations in BP blister fluids (10, 11). Similar skin lesions are observed in the pregnancy-associated nonviral disorder herpes gestationis (12). These observations imply that MCs may play a role in blister formation.We have used an experimental model of BP that involves the passive transfer of anti-mBP180 antibodies into neonatal BALB/c mice to reproduce the key immunopathological features of this human autoimmune disease: IgG and complement deposition at the DEJ, inflammatory infiltration of the upper dermis, and subepidermal blistering (13). The pathogenicity of anti-mBP180 antibodies depends on complement activation (14) and polymorphonuclear leukocyte (PMN) recruitment (15). In the present study, we have investigated the role of MCs in experimental BP using mice genetically deficient in MCs. Preparation of pathogenic rabbit anti-mouse IgG. The preparation of recombinant mBP180 and the immunization of rabbits were performed as described previ-
Methods
Laboratory animals. Breeding pairs of MC-deficient WCB6F1-Mgf