IgA antikeratinocyte surface autoantibodies from two types of intercellular IgA vesiculopustular dermatosis recognize distinct isoforms of desmocollin

We previously proposed the term intercellular IgA vesiculopustular dermatosis (IAVPD) for cases showing IgA antikeratinocyte surface autoantibodies. This condition is divided into two subtypes: intraepidermal neutrophilic IgA dermatosis (IEN), showing pustule formation in the entire epidermis, and subcorneal pustular dermatosis (SPD) showing pustule formation in the uppermost epidermis. We have previously reported that serum from certain IAVPD patients reacts with bovine desmocollin (Dsc), a desmosomal cadherin. In this study rye showed that two Dsc isoforms with a slightly different molecular weight were recognized by the serum from these patients. Further analysis revealed that serum from patients with the SPD type, which stained the cell surface in the uppermost epidermis with immunofluorescence, seem to react with Dsc1. By contrast, serum from patients with the IEN type, which stained the cell surface at all levels of the epidermis with immunofluorescence, seemed to react with Dsc3. This difference of distribution between the two distinct Dsc molecules may contribute to the different clinicopathological features between the IEN and SPD type of IAVPD.