Bullous pemphigoid and antinuclear antibodies. Unmasking of basement membrane fluorescence in sodium chloride-treated substrates.

Immunoflourescent (IF) microscopic studies were done on a patient with bullous pemphigoid who had a high titer of antinuclear antibodies (ANAs). Direct IF microscopy showed deposition of lgG and C3 at the basement membrane zone (BMZ), while, by indirect IF microscopy, ANAs (but not circulating pemphigoid antibodies) were detected. The 2M sodium chloride (NaCl) solution-treated substrates, in which nuclear antigens were eluted, uncovered pemphigoid antibodies. Treatment of the substrates with NaCl solution unmasked BMZ fluorescence in another set of experiments in which a large amount of serum samples containing ANAs was added to serum samples containing only pemphigoid antibodies. These results suggest that pemphigoid antibodies are able to react to the BMZ in the presence of concomitant ANAs unless bind to the nuclear antigens.