Bullous pemphigoid antibodies. Human skin as a substrate for indirect immunofluorescence assay

Human skin, the target organ for bullous pemphigoid (BP) antibodies, is thought to be a less sensitive substrate for the indirect immunofluorescence assay of BP antibodies than monkey or guinea pig esophagus. To examine the reasons for this puzzling phenomenon, we compared the titers of BP antibodies obtained when human skin, monkey, and guinea pig esophagus were used as substrates. We found the titers of BP antibodies obtained with human skin from sites commonly involved in BP (flexor arm, flexor thigh, popliteal fossa) were as high and usually higher than those obtained with monkey and guinea pig esophagus. In contrast, much lower titers were obtained with human skin from sites rarely involved in the disease (scalp, face, extensor arm). These findings suggest that human skin as a substrate is at least as sensitive as monkey or guinea pig esophagus for the indirect immunofluorescence assay of BP antibodies when the skin is obtained from regions on the body commonly involved in BP.