Abstract: In order to study the antigenic epitope on the BP180 and the relationship between the autoantibodies in bullous pemphigoid (BP) sera and BP180 NC16a fusion protein, we examined sera from 64 BP and 2 cicatricial pemphigoid (CP) patients using immunoblotting technique with the fusion protein covering the entire BP180 NC16a domain expressed by prokaryotic bacteria. The results showed that 48 of the 64 BP sera (75.0%) reacted with this fusion protein, which was higher than that with normal human epidermal extracts (43 positive, 67.2%). However, the difference between them was not statistically significant. All 9 CP sera also recognized the fusion protein. The results also indicated that the entire BP180 NC16a domain contains most epitopes of BP180 autoantibody, which represents the important part of BP180 autoantigen. The antibodies of BP and CP share a common antigenie site. Although there are now some limitations of using BP180 NC16a fusion protein in clinical diagnosis, it might be of use in the study of the pathogenesis and differential diagnosis of bullous diseases.

Key words: Pemphigoid, Fusion protein, Immunoblotting