Serologic abnormalities in patients with endemic pemphigus foliaceus (Fogo selvagem), their relatives, and normal donors from endemic and non-endemic areas of Brazil.

Based on epidemiologic data, a current hypothesis states that Fogo selvagem (FS) may be triggered by environmental factors present in endemic areas of Brazil. Because the appearance of new cases is limited to those areas, we wanted to ascertain if the presence of the pemphigus autoantibodies was restricted to the patients. To further delineate the restriction of the autoantibody response in these patients we also investigated the presence of lupus-associated autoantibodies. Using indirect immunofluorescence (IF) we tested the sera of patients with FS (n = 196), their relatives (n = 138), their cohabitants (n = 13), and normal donors from endemic (n = 38) and non-endemic areas (n = 44) for pemphigus autoantibodies. Antinuclear antibodies (ANA) and anti-nDNA antibodies were determined by indirect IF against Hep-2 cells and Crithidia lucilliae, respectively. Autoantibodies against nRNP, Ro/SSA, La/SSB, and Sm were assayed by double immune diffusion in agarose gels. FS autoantibodies were present in the sera of all patients with active disease (n = 196, 100%, titers greater than 40 to 2560), but were not found in any sera from normal individuals in endemic or non-endemic areas. The titer of the FS autoantibody showed a rough correlation with the extent and activity of the disease. Furthermore, lupus-associated autoantibodies were not present in any of the tested samples. We conclude the FS antiepidermal autoantibodies are specific serologic markers of the disease and are not present in unaffected individual from the endemic areas. As such, they provide an important marker that should be useful in ongoing epidemiologic studies aimed at identifying putative etiologic agent(s).