Case of pemphigus with immunoglobulin G and A antibodies, binding to both the intercellular spaces and basement membrane zone

Antigen recognition in the pathogenesis of immunoglobulin A-related autoimmune bullous diseases

Immunoglobulin A (IgA) is the most common subtype of antibodies in mucosal surfaces. In most of autoimmune bullous diseases, however, immunoglobulin G (IgG) is the main pathogenic antibody that plays a role through complementation. The IgA antibody for epidermal connection protein can be found in the sera of some patients with blistering skin disease. Of these patients, some have the IgA antibody in their sera, while others have IgG and IgA antibodies. IgA-related autoimmune bullous diseases are less common in clinical practice. In the past, these diseases were not fully understood and their classifications were confusing. Recently, some progress has been made in the study of these diseases.

Case of bullous pemphigoid coexisting with anti-desmoglein autoantibodies

A 79-year-old Japanese woman had clinical and histopathological features of bullous pemphigoid, while direct immunofluorescence test revealed C3 and immunoglobulin G depositions in the lower cell surfaces of the epidermis in addition to those in the dermoepidermal junction. Chemiluminescent enzyme immunoassays were positive for desmoglein-1 and -3 antibodies in addition to anti-BP180 antibodies. In an immunoblotting study, antibodies against both 180-kDa bullous pemphigoid antigen and 130-kDa pemphigus vulgaris antigen were detected. Based on these results, bullous pemphigoid coexisting with anti-desmoglein autoantibodies was diagnosed in this case.

Pemphigus, a pathomechanism of acantholysis

Autoantibodies to the desmosomal proteins desmoglein 1 and 3 cause pemphigus foliaceus and pemphigus vulgaris, which are characterised by keratinocyte dissociation (acantholysis) and intraepidermal blister formation. The passive transfer of pathogenic anti-desmoglein antibodies induces blisters in mice in vivo and the loss of keratinocyte adhesion in vitro. The pathogenetic mechanisms of acantholysis due to anti-desmoglein autoantibodies are not fully understood. However, recent studies have revealed that signalling-dependent and signalling-independent pathways are operative in the loss of cell adhesion. In this review, we focus on the pathomechanism of acantholysis due to autoantibodies to desmogleins and recent therapeutic approaches.