Algorithm for antinuclear antibodies in subjects with clinical suspicion of autoimmune diseases

• Published in: Clinical and experimental rheumatology Vol. 38; no. 4; p. 633
• Main Authors: Naranjo, Laura, Shovman, Ora, Pérez, Dolores, Infantino, María, Cabrera-Marante, Oscar, Lozano, Fernando, Gilburd, Boris, Manfredi, Mariangela, Serrano, Manuel, Morillas, Luis, Shoenfeld, Yehuda, Serrano, Antonio
• Format: Journal Article
• Language: English
• Published: 01.07.2020
• ISSN: 0392-856X

Antinuclear antibodies (ANA) are fundamental in the diagnosis of systemic autoimmune rheumatic diseases (SARDs). Different assays for ANA screening are available, such as indirect immunofluorescence (IIF) on HEp-2 cells and Multiplex fluorescent immunoassay (MFI). This study aimed to clarify the importance of ANA detected only by IIF in the future development of SARDs and to recommend a laboratory algorithm that integrates the available diagnostic approaches to optimise the diagnosis of ANA IIF+MFI- subjects.OBJECTIVESAntinuclear antibodies (ANA) are fundamental in the diagnosis of systemic autoimmune rheumatic diseases (SARDs). Different assays for ANA screening are available, such as indirect immunofluorescence (IIF) on HEp-2 cells and Multiplex fluorescent immunoassay (MFI). This study aimed to clarify the importance of ANA detected only by IIF in the future development of SARDs and to recommend a laboratory algorithm that integrates the available diagnostic approaches to optimise the diagnosis of ANA IIF+MFI- subjects.A total of 9,291 subjects with clinical suspicion of SARDs were evaluated for ANA by IIF and MFI. One hundred and ninety-eight subjects (2.1%) were ANA IIF+MFI-, who were followed up for 2 years. ANA were evaluated using IIF on HEp-2 cells and MFI on the BioPlex 2200.METHODSA total of 9,291 subjects with clinical suspicion of SARDs were evaluated for ANA by IIF and MFI. One hundred and ninety-eight subjects (2.1%) were ANA IIF+MFI-, who were followed up for 2 years. ANA were evaluated using IIF on HEp-2 cells and MFI on the BioPlex 2200.The ANA IIF+MFI- cohort included 106 subjects with SARDs, 26 subject with other autoimmune diseases (not-SARDs) and 66 subjects with minor symptoms or ANA requested in check-ups. Only 94 subjects underwent re-evaluation. After a 2-year follow-up, most re-evaluated subjects (51 patients) became ANA negative for both assays (mainly rheumatoid arthritis, polymyalgia and inflammatory bowel disease patients) and 35 subjects remained ANA IIF+MFI- (principally systemic sclerosis and systemic lupus erythematosus patients). A new algorithm for ANA evaluation was suggested.RESULTSThe ANA IIF+MFI- cohort included 106 subjects with SARDs, 26 subject with other autoimmune diseases (not-SARDs) and 66 subjects with minor symptoms or ANA requested in check-ups. Only 94 subjects underwent re-evaluation. After a 2-year follow-up, most re-evaluated subjects (51 patients) became ANA negative for both assays (mainly rheumatoid arthritis, polymyalgia and inflammatory bowel disease patients) and 35 subjects remained ANA IIF+MFI- (principally systemic sclerosis and systemic lupus erythematosus patients). A new algorithm for ANA evaluation was suggested.According to the proposed algorithm, ANA IIF+MFI- subjects should be screened by an alternative solid-phase assay such as line-immunoassay or ELISA.CONCLUSIONSAccording to the proposed algorithm, ANA IIF+MFI- subjects should be screened by an alternative solid-phase assay such as line-immunoassay or ELISA.