Direct immunofluorescence on uninvolved, lesional and perilesional skin in patients with endemic pemphigus foliaceus (fogo selvagem)

Research on direct immunofluorescence in pemphigus foliaceus ("fogo selvagem") has been focused mainly on the study of perilesional and lesional skin, while little attention has been given to uninvolved skin. We analyzed the frequency of IgA, IgM, IgG and its subclasses (IgG1, IgG2, IgG3 and IgG4) and C3 complement fraction deposition in intercellular spaces (ICS) and basal membrane zone (BMZ) in uninvolved, lesional and perilesional skin from 47 fogo selvagem patients. For each patient biopsies were collected from lesional, perilesional and uninvolved skin, and then analyzed by direct immunofluorescence. The panel of antibodies consisted of IgA, IgM, IgG and its subclasses (IgG1, IgG2, IgG3 and IgG4) and C3 complement fraction. The results showed a predominance of IgG and IgG4 deposit in all skin samples, followed by C3 complement fraction and IgG1 deposits. The positive response for IgG on uninvolved (91.48%), lesional (93.61%) and perilesional (97.87%) skin was similar to that found for IgG4 in the same samples: 95.74%, 95.74% and 97.87%, respectively. Regarding IgG1, the uninvolved skin showed lower results (14.89%) than the lesional (29.78%) and perilesional skin (29.78%). Concerning C3 complement fraction, the perilesional skin showed higher results (40.42%) than the uninvolved and lesional skin (34.04% for both). The results suggest the importance of uninvolved skin for direct immunofluorescence in the diagnostics of pemphigus foliaceus. Our results suggest that any cutaneous region can demonstrate pemphigus antibodies by direct immunofluorescence.