We applied confocal
laser scanning microscopy to fluorescence overlay
antigen mapping (FOAM) for differential diagnosis of
bullous pemphigoid (BP) and
epidermolysis bullosa acquisita (EBA). FOAM of tissue-bound
IgG and marker basement membrane components (BMCs) including
integrin beta 4,
laminin-1,
laminin-5 and
type IV collagen, showed that tissue-bound
IgG in perilesional skin samples from five patients with BP was localized on the epidermal side of
type IV collagen, and colocalized with some of the other three BMCs, whereas
IgG in a sample from a patient with EBA was on the dermal side of all the BMCs. FOAM of binding sites of
autoantibodies in patients' sera and markers including
integrin beta 4,
laminin-1,
type IV collagen and
type VII collagen, showed that the binding sites of
autoantibodies from 16 patients with BP were localized on the epidermal side of type IV and type VII
collagens, and localized above or codistributed with
integrin beta 4 and
laminin-1, whereas those from five patients with EBA were codistributed with type IV and type VII
collagens, and localized on the dermal side of
integrin beta 4 and
laminin-1. These spatial relationships are compatible with their previously described ultrastructural locations. Thus, this method appears to be useful in the differential diagnosis of BP and EBA.