RESUMO
Anti-extractable nuclear antigen (ENA) antibodies were assayed by counter immunoelectrophoresis (CIE) and immunoblotting in patients with systemic lupus erythematosus (SLE). We found the two methods showed good concordance rates, the lowest being 67% for anti-SS-A. Immunoblotting was more sensitive in detecting anti-Sm, anti-SS-B and anti-PCNA (proliferating cell nuclear antigen); CIE was more sensitive for anti-nRNP and anti-SS-A. Overall, the prevalence of these anti-ENA antibodies in SLE was increased by 9-20% if immunoblotting was used in addition to CIE. Sera specific for the 52 kDa peptide of the SS-A antigen (anti-52kDa SS-A) were better detected by immunoblotting. Anti-PCNA antibody was found in 6.3% of SLE patients and was associated with active disease and hemolytic anemia. The positive rate of anti-Sm was 9% by CIE and 23.7% by immunoblotting and this antibody was a specific marker for SLE using either method. It was concluded that using immunoblotting in addition to CIE, the overall sensitivity of detection of anti-ENA antibodies in SLE was increased and clinically useful antibodies such as anti-52kDa SS-A and anti-PCNA could be detected.
Assuntos
Anemia Hemolítica/sangue , Anticorpos Antinucleares/análise , Especificidade de Anticorpos/imunologia , Autoantígenos/imunologia , Biomarcadores/sangue , Progressão da Doença , Humanos , Immunoblotting , Imunoeletroforese , Lúpus Eritematoso Sistêmico/sangue , Antígeno Nuclear de Célula em Proliferação/imunologia , RNA Citoplasmático Pequeno , Ribonucleoproteínas/imunologia , Ribonucleoproteínas Nucleares Pequenas , Sensibilidade e Especificidade , Proteínas Centrais de snRNPRESUMO
The streptavidin-biotin-peroxidase complex (SABC) technique was compared to conventional indirect immunofluorescence (IIF) for the detection of anti-nuclear antibody (ANA) on HEp-2 cell substrate. SABC showed higher specificity and predictive value and gave more reproducible titres and clearer staining patterns than IIF in sera from a series of rheumatic disease patients. Sera from 80 patients with various types of rheumatic diseases and 20 without rheumatic disease were further tested using the SABC method. All systemic lupus erythematosus (SLE) sera were positive. The overall sensitivity was 95%, specificity 90% and predictive value 97% for rheumatic disease. The rim pattern was associated with SLE and mixed connective tissue disease. The nucleolar/homogeneous pattern was associated with scleroderma and SLE in remission. ANA titre and staining pattern have limited value in the clinical assessment of rheumatic disease; however, ANA has very high sensitivity for SLE and remains an excellent screening test.