[Herpes gestationis: immunologic and immunogenetic aspects]

Herpes gestationis or pemphigoid gestationis (PG) is a bullous disease developing in association with pregnancy. It is believed to be an immunologically mediated disorder. Antibody binding by specific autoantibodies was detected in placental tissue and in the area of the hemidesmosomes and the basal membrane zone of the skin. These autoantibodies react with antigens of 180 kDa and 230 kDa relative molecular mass, which are presumably identical to the bullous pemphigoid antigen BPAG1 and BPAG2. The herpes gestationis factor (HG factor) preferentially binds to the 180-kDa antigen (BPAG2). The involvement of specific autoantibodies against adhesion molecules suggests the involvement of an aberrant immune response. Several groups have reported an association of pemphigoid gestationis to alleles of the human leukocyte antigens; HLA-B8 (class I) and HLA-DR3 and HLA-DR4 (class II), encoded on the short arm of chromosome 6. The unique feature of pemphigoid gestations is compared with other bullous dermatoses the association with the hormonal regulation during pregnancy and the presence of allogenic tissue. The hormonal regulation at the level of gene expression, possibly including gene expression of non-classic HLA class I molecules such as HLA-G, may be a cofactor in the pathogenesis of pemphigoid gestationis. This account, together with a case report, discusses the association of pemphigoid gestationis with HLA and a putative pathophysiological role of the newly described non-classical HLA molecules encoded in the MHC.