P040\u2005The european consensus finding study group on autoantibodies 2017/18 investigation. Characterisation of autoantibody content in a new international reference standard for dense fine speckled 70kD (DFS70) autoantibodies

Abstract

Career situation of first and presenting author Instructor. Introduction The European Consensus Finding Study Group on autoantibodies (ECFSG) a.k.a. the EULAR autoantibody study group has been active for 30 years. Objectives To reach consensus about autoantibody measurements in clinical practice, and to evaluate upcoming autoantibody standard reagents concerning autoantibody content. Methods ECFSG focus on evaluating difficult to interpret serum samples, where differences between assays can be clearly visible. Ten unknown samples are distributed yearly to European laboratories, and analyzed broadly. Results are collected with information about laboratory techniques used, and discussed in relation to clinical information on the donating patients during EWRR. The 2017/2018 investigation contained nine patient samples, and a not yet launched pooled standard for anti-dense fine speckled 70kD antibodies, an ANA reactivity with specific nuclear staining on HEp-2 cells that can be confounded with homogenous ANA, but that is not associated with autoimmune disease. Results Acceptable consensus was reached for the clinical samples. Anti-DFS70 pattern was reported from 32/38 laboratories, whereas 5/38 reported homogenous ANA, one reported unknown pattern. Except for 4 out of 24 laboratories reporting anti-histone and 2 out of 33 laboratories reporting ACPA, both in low levels, no autoantibodies were reported. Consensus was that the sample contained pure anti-DFS70. Conclusions ECFSG helps to keep awareness on differences between autoantibody assays. The anti-DFS70 ANA pattern was identified by most laboratories in a reagent that proved to be free of other autoantibodies. The anti-DFS70 standard will be available via http://asc.dental.ufl.edu/ReferenceSera.html#text. *Lab representatives: Renaudineau Y, Brest; Fricke M, Hannover; Shoenfeld Y, Sheba, Israel; Nozal Aranda P, Madrid; Tzioufas AG, Athens; Kozakova D, Piestany; Toubi E, Haifa, Israel; Franceschini F, Brescia; Hennessy L, Glasgow; Roux-Lombard P, Genève; Heijnen I, Basel; Karlsen R, Oslo; Jeremie W, Luxembourg; Bombardieri S, Pisa; Cucnik S, Ljubljana; Huber AR, Aarau; Roozendal C, Groningen; Goetz J, Strasbourg; Vencovsky J, Praha; Wojciechowska B, Warsaw; Guerti K, Antwerp; Hänninen A, Turku; McHugh N, Bath; Steiner G Wien; Schreurs M, Rotterdam; Montes Cano MA, Sevilla; Elvin K, Stockholm; Nagy E, Budapest; Babai I, Tikva, Israel; Bonroy C, Gent; Burmester GR, Berlin; Andrejevic S, Belgrade; Kral V, Usti nad Labem; Csernok E, Tübingen; Probst-Mueller E, Zürich; Fischer K, Szczecin; Hacein-Bey-Abina S, Paris; Conrad K, Dresden; Humbel RL, Leudelange. Disclosure of Interest None declared.