During the second trimester of pregnancy, a patient developed herpes gestationis characterized by a widespread eruption of iris lesions with peripheral subepidermal vesicles and severe blood eosinophilia. Direct immunofluorescent studies of lesions showed deposition of IgG, C1q, C3, and properdin at the basement membrane, implicating both classic and alternate complement pathway activation. A circulating antibody to basement membrane, previously undescribed, to our knowledge, in this disease, was found, which suggests that herpes gestationis may be related to bullous pemphigoid.
Bushkell LL, Jordon RE, Goltz RW. Herpes GestationisNew Immunologic Findings. Arch Dermatol. 1974;110(1):65-69. doi:10.1001/archderm.1974.01630070033005