Experimental bullous pemphigoid generated in mice with an antigenic epitope of the human hemidesmosomal protein BP230 (1)
Immunodominant and pathogenic epitopes of BP180 associated with BP have been mapped to the NC16A domain, a membrane proximal non-collagenous stretch of the extracellular portion. Autoantibodies to BP180 associated with BP can release interleukin-6 and interleukin-8 from cultured human keratinocytes and can induce dermal-epidermal separation in cryosections of human skin. The other autoantigen of BP is a hemidesmosomal cytoplasmic plaque protein that belongs to a family of intermediate filament binding plakin proteins. BP230 is a major isoform of the BPAG1 gene expressed in the epidermis. Major antigenic epitopes of BP230 map within the C-terminal end of the protein. The C-terminal domain of BP230 is associated with keratin intermediate filaments.
The chosen epitopic fragments were as follows. Schematic diagrams of the recombinant proteins and sequence comparisons of the human and murine proteins BP230 and BP180 are illustrated.
BP1: WTQEPQPLEEKWQHRVVEQIP (BP230, AC Q03001; 2479e2499),
BP2: RSILPYGDSMDRIEKDRLQGMAP (BP180, AC Q02802; 507e528).
All 4 rabbit sera (2 immunized with GST-BP1112 and 2 with GST-BP22) showed linear rabbit IgG deposition along the basement membrane on normal human skin cryosections and on the epidermal part of the basement membrane on human salt-split skin sections. The rabbit sera immunized with GST-BP1112 revealed the characteristic pattern of BP on human epidermal protein extracts by the Western blotting technique.
Neonatal CBA mice (12-24 h old) were given sub- cutaneous injections of different doses (5.0 mg or 1.2 mg IgG/50 ml) of purified IgG fractions prepared from the rabbit anti-GST-BP1112 and anti-GST-BP22 antisera and control rabbit IgG. Clinical, immunohistological and histological data are presented.
The dorsal skin areas of most of the anti-GST-BP1112- injected animals were constantly erythematous and gentle friction produced a fine persistent wrinkling of the epidermis, and 2 animals exhibited blisters clinically.
