Anti-intercellular substance antibodies. Presence in serum samples of 14 patients without pemphigus.

Fourteen of 1,500 patients whose serum samples were evaluated by indirect immunofluorescence microscopy had demonstrable titers of anti-intercellular substance (ICS) antibodies in the absence of clinical or histologic evidence of pemphigus. The anti-ICS antibodies were absorbed by A and B blood group antigens in nine of the 14 patients. In five patients, the titers of anti-ICS antibodies were unchanged after absorption with blood group substances. All five of these patients had cicatricial or bullous pemphigoid on clinical, histologic, and immunopathologic examination. Clinical pemphigus did not develop in any of the 14 patients on follow-up examinations conducted for three to 18 months. It seems that anti-ICS antibodies can be produced in several clinical conditions in which there is damage to the epidermis. These anti-ICS antibodies may not have any pathogenetic activity in vivo, at least within the time limits defined by our follow-up examinations.