Identification of basement membrane zone antigens defined by antibodies that react to both the epidermal and dermal side of 1 M sodium chloride split skin.

Some individuals have basement membrane zone (BMZ) antibodies that react to both the epidermal and dermal side of skin split with 1 M NaCl. To examine the significance of this combined staining pattern, we tested sera from 185 different, sequential, patients with BMZ antibodies for reactivity to normal human skin split with 1 M NaCl. Six sera (3.2%) stained both the epidermal and dermal sides of split skin, 173 (93.5%) stained only the epidermal side, and 6 (3.2%) only the dermal side. All six sera with a combined staining pattern yielded the same pattern when tested with three different specimens of skin, indicating that this pattern is reproducible. By immunoblot analysis, five (83%) of the six combined staining sera reacted to a 160-kD antigen present only in epidermal extracts of normal skin, one reacted in addition to a 230-kD epidermal antigen, and one did not react to either epidermal or dermal extracts. In contrast, five (83%) of the six sera with dermal staining reacted to a 290-kD antigen present only in dermal extracts. Eighteen (90%) of twenty representative epidermal staining sera reacted to a 230-kD epidermal antigen and seven (35%) sera (five with the 230-kD antibody and two without) also reacted to the 160-kD epidermal antigen. Affinity purified antibody to the 160-kD antigen defined by combined staining sera reacted to the BMZ of normal human skin. These results indicate that the combined staining pattern on 1 M NaCl split skin is due to the presence of a distinctive antibody response directed predominantly to a 160-kD BMZ antigen located on the epidermal side of the split skin and to an as yet unidentified BMZ antigen located on the dermal side.