Polymorphisms of HLA class II genes in Japanese patients with pemphigus vulgaris.

Pemphigus vulgaris (PV) is an autoimmune disease mediated by autoantibodies that bind to a keratinocyte adhesion molecule, desmoglein-3. The purpose of this study was to identify critical amino acid residues of PV-associated HLA class II genes. Haplotype and allele distributions, along with molecular polymorphisms, of HLA class II genes were analyzed based on the polymerase chain reaction-restriction fragment length polymorphism in 17 Japanese PV patients. Each patient had one or two alleles of DRB1*04 (*0403, *0404, *0406) or DRB1*14 (*1401, *1405, *1406) subtypes. All DRB1*04 and DRB1*14 alleles carried by PV patients with different ethnic backgrounds reported to date, including DRB1*0402, which confers strong susceptibility to PV among Jewish populations, have amino acid residues Phe26, Leu67 or Ile67, and Val86, as well as hydrophilic amino acid residues at positions 70 and 71 of the DRB1 beta chain.