Immunofluorescent Studies of Autoantibodies to Intercellular Areas of Epithelia in Brazilian Pemphigus Foliaceus

Summary Sera of patients with fogo selvagem or BPF (Brazilian pemphigus foliaceus) were found to contain antibodies reactive with the intercellular areas of stratified squamous epithelium of esophagus and skin as revealed by indirect IF (immunofluorescent) staining. These intercellular antibodies could not be distinguished histologically from those associated with nonendemic pemphigus (i.e., the forms of pemphigus which occur in rest of the world). The following observations were made on these antibodies: (1) Only sera of patients with pemphigus were found to contain these intercellular antibodies. None of 56 control sera yield such staining patterns. (2) Indirect IF staining titers of the intercellular areas could be determined reproducibly ± 1 doubling dilution in the two participating laboratories in a double blind study of 29 sera. (A 30th serum is discussed under point 5 below.) (3) The titers of intercellular antibodies appeared to be proportional to the severity of the disease process in BPF. (4) These titers were approximately 8-fold higher than those found in cases of nonendemic pemphigus of comparable severity. (5) One serum specimen from a patient with BPF yielded variable titers initially. Circumstantial evidence indicates that this may have been due to the presence of rheumatoid factor which acts as an inhibitor. Three subsequent serum specimens of this patient yielded titers in the range expected with the clinical condition of the patient.