Skin explant culture: a reliable method for detecting pemphigoid antibodies in pemphigoid sera that are negative by standard immunofluorescence and immunoblotting.

We investigated the presence of bullous pemphigoid antibodies in bullous pemphigoid sera that are negative by standard indirect immunofluorescence. We incubated each of four indirect immunofluorescence-positive bullous pemphigoid sera, seven indirect immunofluorescence-negative bullous pemphigoid sera, one indirect immunofluorescence-negative herpes gestationis serum, three indirect immunofluorescence-positive epidermolysis bullosa acquisita sera, five indirect immunofluorescence-negative epidermolysis bullosa acquisita sera, and two normal human sera with fresh human skin explants in medium 199 at 4 degrees C for 48 h. All bullous pemphigoid sera, herpes gestations serum, and the three indirect immunofluorescence-positive epidermolysis bullosa acquisita sera had IgG that bound the basement membrane zone of skin explants with moderate to marked intensity as demonstrated by immunofluorescence. Normal sera and indirect immunofluorescence-negative epidermolysis bullosa acquisita sera failed to bind the explant basement membrane zone. Immunoblotting of bullous pemphigoid sera showed five of seven indirect immunofluorescence-negative bullous pemphigoid sera to bind high-molecular weight and/or low-molecular weight bullous pemphigoid antigens from epidermal extracts. We conclude that the skin explant culture system is a very sensitive method for the detection of bullous pemphigoid antibodies in all bullous pemphigoid sera.