AB0748 Study of antinucleolar pattern sera in an autoimmunity laboratory: antigenic specificities and clinical association
Authors: R. Téllez, C. Serrano, C. Vegas, P. Tramón, M. J. Rodríguez, F. Romero, O. Sanchez, M. J. Martínez
Journal: Annals of the Rheumatic Diseases (2013)

<h3>Background</h3> Indirect ImmunoFluorescence (IIF) nucleolar pattern has a low prevalence, being usually associated with Systemic Sclerosis (SSc). Despite the increasing number of tools that help us to identify antigenic specificities many nucleolar sera are not yet well characterized. <h3>Objectives</h3> Identify antigenic specificities of sera that exhibit nucleolar pattern by IIF using the current methods available in an Autoimmunity Laboratory and investigate clinical association. <h3>Methods</h3> The study included sera that were sent to our Laboratory to test Antinuclear Antibodies (ANA) from Nov. 2010 to Dec. 2012. Sera were screened by IIF (HEp-2, INOVA®). Nucleolar sera were further studied by ANA ELISA, ENA ELISA and RNAPol-III ELISA (QUANTA Lite® INOVA), PMScl (either by ELiA® or Immunoblot -BlueDot. D-tek®-), Fibrilarin, Scl-70 and Ro (ELiA® IgG InmunoCap Phadia®). Anti Nor-90 antibodies were analized by an external Laboratory. Clinical data were collected by systematic review of patients' records. <h3>Results</h3> Nucleolar pattern was found in 68 (0.64%) out of 10568 sera studied by IIF. Mean age: 56 years (SD ±15). Female:Male ratio 2.77. The most prevalent pattern was clumpy nucleolar associated with diffuse nucleoplasm (56%). 62% of sera exhibited negative chromatin. Clinical diagnostics were: 35% (24) Connective Tissue Disease (CTD), 22% (15) Liver diseases, 43% (29) Other clinical features (Other). Among CTD, SSc was the most frequent diagnosis (62%). In 72% of sera no antigenic specificities were found. RNAPol-III and Scl-70 were the most frequently specificities identified: 10% (7) and 9% (6), respectively. All antiRNAPol-III positive showed diiffuse nucleoplasm, 71% (5) exhibited speckled nucleoli and 71% (5) had negative chromatin. Among positive Scl-70 all exhibited diffuse nucleoplasm, 67% (4) showed clumpy nucleoli and 67% (4) had positive chromatin staining. Only antiScl-70 specificities were in all cases detected by both ANA and ENA ELISA. No antigenic specificities were found in the group Liver diseases. In the group CTD 62% (15) were found an antigenic specificity: 25% Scl-70 (6), 21% RNAPol-III (5), 12% PMscl (3) and 4% Fibrilarin (1). Among the group Other 14% (4) had an antigenic specificity: 7% RNAPol-III (2), 3% Fibrilarin (1) and 3% Nor-90 (1). <h3>Conclusions</h3> Nucleolar pattern has low prevalence, frequently presenting a mixed IIF pattern. Despite the classical association of nucleolar pattern with CTD we describe a high prevalence among other clinical settings. There are a high percentage of nucleolar sera in which antigenic specificities have not been identified, specially gathered in Liver diseases' group. In our study there is a cohort of patients that have not currently a definitive CTD diagnosis but exhibit characteristic antigenic specificities. A follow up must be considered in these patients to track future clinical implications. This might confirm the importance of studying nucleolar sera despite the absence of a current clinical suspicion. <h3>References</h3> <i>Antibodies to fibrillarin, PM-Scl and RNA polimerasa III detected by ELISA assays in patients with systemic sclerosis. Villalta et al, 2010</i> <i>Atlas of Hep-2 patterns. Third edition. A.R Bradwell, R.G Hughes. The Binding Site Ltd, 2007</i> <h3>Disclosure of Interest</h3> None Declared