{
  "abstract": "Introduction The presence of autoantibodies is a hallmark of systemic sclerosis (SSc). They are helpful for the diagnosis of SSc and are associated with distinct clinical manifestations and prognosis. Several commercially available platforms have been developed for the detection of autoantibodies including line blot. Nonetheless, indirect immunofluorescence assay on HEp-2 cells (HEp-2/IFA) is the most frequent method used worldwide for the screening of autoantibodies in patients with systemic autoimmune diseases. This study aimed to evaluate the agreement between two HEp-2-IFA kits and the detection of SSc-specific and SSc-associated antibodies using line blot in SSc patients.Material and Methods Serum samples of 188 patients who fulfilled the ACR/EULAR classification criteria for SSc were included. Hep-2 IFA were analyzed using two kits (Euroimmun and AESKU) and were considered positive at 1:80 dilution. The HEp-2-IFA patterns were evaluated by two professionals and were expressed according to the ICAP nomenclature (www.anapatterns.org). The detection of SSc-specific (anti-Scl-70, anti-CENP-A/B, anti-Th/To and anti-fibrillarin) and associated antibodies (anti-PmScl-75/PmScl-100 and anti-NOR90) was performed using line blot from Euroimmun (EUROLINE SSc IgG profile). Agreement between the HEp-2 IFA patterns and the line blot assay were calculated and expressed using Cohen’s kappa (k) coefficient.Results In HEp-2 IFA, 89.9% (Euroimmun) and 90.4% (AESKU) of the samples were positive; interobserver agreement was 91% and 94%, respectively. EUROLINE line blot testing was positive in 72.3% of samples. The centromeric pattern (AC-3) in both Euroimmun and AESKU slides showed 99% agreement with anti-CENP-A/B in the line blot (k=0.967; p<0.001). The topoisomerase I pattern (AC-29) showed 97.4% (Euroimmun) and 98.4% (AESKU) agreement with anti-Scl-70 in the line blot (k=0.915 and 0.950, respectively; p<0.001). For the homogeneous nucleolar pattern (AC-8) 87.2% (Euroimmun) and 88.3% (AESKU) agreement with anti-PmScl-75/PmScl-100/Th-To in the line blot was found (k=0.448 and 0.494, respectively; p<0.001). The speckled nucleolar pattern (AC-10) showed 95.8% (Euroimunn) and 95.7% (AESKU) agreement with anti-NOR-90 in the line blot (k=0.311 and 0.407, respectively; p<0.001). The clumpy nucleolar pattern (AC-9) in both slides showed 91.5% agreement with anti-fibrillarin in the line blot, without statistical significance (k=0.087; p=0.102).Conclusions There was almost perfect agreement between HEp-2 IFA and line blot for the centromeric (CENP-A/B) and topoisomerase I (Scl-70) patterns. Moderate agreement was observed for the homogeneous nucleolar pattern (PmScl-75/100, Th/To) and low agreement was found for other patterns. These findings reinforce the usefulness of HEp-2 IFA as a cost-effective screening test and the good consistency with specific autoantibodies confirmed by line blot.",
  "authors": [
    {
      "affiliations": [
        "Federal University of Sao Paulo - Department of Medicine - Rheumatology Division, Sao Paulo, Brazil"
      ],
      "name": "Pedro Matos"
    },
    {
      "affiliations": [
        "Federal University of Sao Paulo - Department of Medicine - Rheumatology Division, Sao Paulo, Brazil",
        "Universidad Católica del Norte - Department of Biomedical Sciences - Faculty of Medicine, Coquimbo, Chile"
      ],
      "name": "Gerson Dierley Keppeke"
    },
    {
      "affiliations": [
        "Federal University of Sao Paulo - Department of Medicine - Rheumatology Division, Sao Paulo, Brazil"
      ],
      "name": "Silvia Helena Rodrigues"
    },
    {
      "affiliations": [
        "Federal University of Sao Paulo - Department of Medicine - Rheumatology Division, Sao Paulo, Brazil",
        "Aesku.Diagnostics - Research & Development, Wendelsheim, Germany"
      ],
      "name": "Trischna Martins"
    },
    {
      "affiliations": [
        "Aesku.Diagnostics - Research & Development, Wendelsheim, Germany"
      ],
      "name": "Claudia Pratas"
    },
    {
      "affiliations": [
        "Federal University of Sao Paulo - Department of Medicine - Rheumatology Division, Sao Paulo, Brazil",
        "Fleury Medicine and Health Laboratories - Immunology Division, Sao Paulo, Brazil"
      ],
      "name": "Luis Eduardo C Andrade"
    },
    {
      "affiliations": [
        "Federal University of Sao Paulo - Department of Medicine - Rheumatology Division, Sao Paulo, Brazil"
      ],
      "name": "Cristiane Kayser"
    }
  ],
  "title": "P.371 Correlation between indirect immunofluorescence assay on HEp-2 cells patterns and specific autoantibodies by line blot in systemic sclerosis patients",
  "uid": "5a09776d-2302-535f-9934-e87097d642f9"
}