We established three lymphoblastoid cell lines from a bullous pemphigoid (BP) patient's peripheral blood by means of EBV transformation, which produced human monoclonal anti-basement membrane zone (BMZ) IgG antibodies. A blocking immunofluorescence test using these MAbs, designated 5A, 5E, and 10D, revealed that 5A and 5E recognized the same or a closely associated epitope, but the epitope for 10D was completely different, 18 of 30 BP sera blocked the reactivity of 10D MAb and 17 sera blocked 5E, while 9 sera did not block the staining of either antibody. Immunoblot analysis demonstrated that both 5A and 5E MAbs reacted exclusively with a protein band of approximately 230 kD in normal human epidermal extracts. However, 10D did not show any protein band. 22 of 30 BP sera strongly reacted with the same 230-kD protein, while none of control sera showed such reactivity. These results clearly demonstrated the heterogeneity of anti-BMZ antibodies in terms of epitopes. These MAbs should be useful in future investigations concerning not only the immunopathology but also the biochemial and molecular analyses of the BP antigen.
T Sugi, T Hashimoto, T Hibi, T Nishikawa