Autoantigens for IgA anti-intercellular antibodies of intercellular IgA vesiculopustular dermatosis

A new disease characterized by the presence of in vivo bound and/or circulating IgA anti-intercellular (IC) antibodies has recently been identified. We propose the term intercellular IgA vesiculopustular dermatosis (IAVPD) for this entity, which seems to be divided clinicopathologically into at least two distinct subtypes: intraepidermal neutrophilic IgA dermatosis (IEN type) and subcorneal pustular dermatosis-like cases (SPD type). Using immunoblot technique, we examined the antigen substances for the IgA anti-IC antibodies in the sera from one Japanese patient with IEN type of IAVPD and three Japanese patients with SPD type. A serum from a patient with IEN type reacted exclusively with a 120-kD protein in both the normal human skin extract and the bovine desmosome sample. Sera from three patients with SPD type reacted specifically with a doublet of 115-kD and 105-kD proteins, which appeared to be identical to desmocollins I and II, well known desmosomal core proteins, in the bovine desmosome sample. IgA antibody from our patients with IAVPD bound to neither pemphigus vulgaris antigen nor pemphigus foliaceus antigen. From these results, we suggest that IAVPD is different from pemphigus and is heterogeneous in terms of the antigens to which IgA autoantibodies bind.