Canine systemic lupus erythematosus. II: Antinuclear antibodies.

The frequency and the specificities of antinuclear antibodies (ANAb) were studied in dogs with systemic lupus erythematosus (SLE) and compared to those found in normal dogs and in dogs with various infectious diseases. Whole ANAb were detected by immunofluorescence. Anti-double-stranded DNA Ab were found in only 2% of SLE dogs, whereas anti-single-stranded DNA Ab were present in 21.4% of SLE dogs and in 26.8% of dogs with infectious disease. Antihistone Ab were frequently observed in SLE dogs (71%) and are essentially directed against trypsin-resistant epitopes of H3, H4 and H2A. The Western blots of nuclear extracts of HeLa cells were recognized mainly by type 1 Ab (30%, reacting with bands of 43, 36, 35, 34, 30 and 27 kDa) and by anti-Sm Ab (12%) associated with anti-RNP Ab. Anti-SSA and anti-SSB Ab were rare.