Expression of a pemphigoid gestationis-related antigen by human placenta

We studied the antigen binding of sera from 25 patients with pemphigoid gestationis (PG) using skin and amnion as substrates in an indirect immunofluorescence technique. In addition, skin was studied after prior incubation with I M NaCl which allows BMZ cleavage through the lamina lucida. Linear BMZ staining was obtained with sera from patients with PG using human amnion as substrate. This was seen with both full-term and second trimester placentae, but not with first trimester placentae. In NaCl incubated skin all sera bound to the epidermal aspect of the separated tissue. The pattern of staining in skin, chemically split skin and amnion was identical to that previously seen with the sera of patients with bullous pemphigoid suggesting that the antigen against which circulating anti-BMZ antigens are directed may be the same in the two conditions.