IGE ANTIBODIES IN SERA FROM PATIENTS WITH BULLOUS PEMPHIGOID ARE AUTOANTIBODIES PREFERENTIALLY DIRECTED AGAINST THE 230-KDA EPIDERMAL ANTIGEN (BP230)

Bullous pemphigoid (BP) is unique among autoimmune skin diseases in wh ich a high serum IgE level has been detected. We sought to determine t he antigenic specificity of these IgE antibodies in 39 BP sera by immu nofluorescence microscopy, immunoblot, and ELISA. The patient's sera c ontained IgG antibodies to 230-kDa (BP230) (n = 20), 180-kDa (BP180) ( n = 9), and both BP230 and BP180 (n = 10) antigens. Serum IgE levels v aried from 29 to 5000 kIU/L (mean +/- SD, 856 +/- 1426 kIU/L), among w hich sera containing Ige antibodies to BP230 had an IgE level on avera ge 4.3 times higher than anti-BP180 sera. IEE antibodies in 18 sera we re found to be autoantibodies reactive either with an epidermal compon ent of basement membrane zone by immunofluorescence microscopy on 1 M NaCl-split skin or with a 230-kDa antigen by immunoblots of cultured h uman keratinocytes.(7) The 230-kDa epidermal antigen recognized by IgE antibodies comigrated with the BP230 as labeled by a specific human m onoclonal antibody. IgE anti-BP230 antibodies in patients' sera were a lways associated with IgG autoantibodies. No sera contained IgE antibo dies to BP180 or to any other epidermal or dermal antigens as verified by immunoblot and ELISA. A good correlation was found between the pre sence of IgE circulating autoantibodies and the level of serum IgE (P < 0.004). IgE antibodies to BP230, like IgG autoantibodies, were mappe d primarily to the C-terminal end of the protein, as they labeled rBP5 5, a BP230 recombinant protein encoded by a cDNA for the C-terminal en d of BP230.