RESUMO
A common finding in the sera of leprosy patients is the presence of antinuclear antibodies (ANA), but their specificity for autologous antigens is unknown. The aim of this work was to investigate the reactivity of these ANA toward the cell nuclei of human skin. ANA were investigated in the sera of 35 patients with lepromatous leprosy by immunofluorescence reactions performed with sections of human skin biopsies (autologous from each patient and healthy human skin obtained from plastic surgery procedures), and compared with the results obtained when rat liver was used as substrate. ANA titer, immunofluorescence pattern, immunoglobulin classes (IgG and IgM) and complement-binding capability were also investigated. When human skin sections were used as substrates, 30 out of 35 patients (85.7%) gave positive ANA tests; most of them gave a 1:4 to 1:16 titer for IgG with an annular pattern and 1:4 for IgM with an annular or a granular pattern. ANA of 30 patients bound C1q and 14 bound C3. However, when rat liver sections were used as substrates only 9 out of 35 cases (27.1%) gave positive ANA tests. These results show that human skin sections are a better substrate to demonstrate the ANA present in the sera of patients with lepromatous leprosy. Their significance in the pathogenesis of tissue damage remains to be investigated.