• In vivo bound C3 was demonstrated by immunofluorescence in lesions of both maternal and infant skin in an immunopathologic study of herpes gestationis. Immunoglobulins and other complement components of both classical and alternative pathways were not found. The serum was also negative for circulating antibody to basement membrane of skin. Maternal serum had a factor present that was able to deposit C3 from fresh normal serum onto the basement membrane zone of skin.
Hemolytic complement titrations showed a decrease of CH50 levels in serum of both classical and alternative pathways in the mother and the classical pathway in the infant, with a decrease of C2 and C4 in both.
To our knowledge, this is the first report of a decrease in serum complement components in herpes gestationis and indicates that complement may not be activated locally.
(Arch Dermatol 113:1069-1072, 1977)