Complement fixation by Brazilian Pemphigus foliaceus autoantibodies.

This study was undertaken to determine if Brazilian Pemphigus foliaceus (BPF) autoantibodies will fix complement as do P. vulgaris (PV) autoantibodies. When sections of human skin were examined following indirect immunofluorescence (IF) staining, BPF autoantibodies reacted with the upper layers of epidermis, while PV autoantibodies were reactive with the lower layers. When tissue culture epidermal cells were used for indirect IF, BPF autoantibodies were not detected after plating until 24 h, while PV autoantibodies reacted within 18 h of plating. Using complement IF staining methods, BPF autoantibodies were found to fix C1q, C4 and C3 to whole skin sections in an intercellular pattern and to the surface of cultured keratinocytes. Although reactive with different epidermal cell surface antigens, autoantibodies in BPF will fix complement in a fashion similar to autoantibodies in PV.