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Objective. To retrospectively evaluate ANCA testing in a cohort of unselected Greek in- and outpatients. Methods. In 10803 consecutive serum samples, ANCA were tested by indirect immunofluorescence (IIF) and ELISA. ELISA in inpatients was performed only on IIF positive sera. Results. Low prevalence (6.0%) of IIF positive samples was observed. Among these samples, 63.5% presented perinuclear (p-ANCA), 9.3% cytoplasmic (c-ANCA) and 27.2% atypical (x-ANCA) pattern. 16.1% of p-ANCA were antimyeloperoxidase (anti-MPO) positive, whereas 68.3% of c-ANCA were antiproteinase-3 (anti-PR3) positive. Only 17 IIF negative outpatients' samples were ELISA positive. ANCA-associated vasculitides (AAV), connective tissue disorders and gastrointestinal disorders represented 20.5%, 23.9%, and 21.2% of positive results, respectively. AAV patients exhibited higher rates of MPO/PR3 specificity compared to non-AAV (93.8% versus 8%). Conclusions. This first paper on Greek patients supports that screening for ANCA by IIF and confirming positive results by ELISA minimize laboratory charges without sacrificing diagnostic accuracy.

BackgroundRheumatoid Arthritis (RA) is a complex, multifactorial autoimmune disease, whose etiopathogenesis involves genetic and environmental factors.ObjectivesThe aim of the study was the assessment of the association of HLA-DRB1*-SE in the presence/absence of anti-CCP autoimmunity in Greek patients with RA (smokers and non-smokers).MethodsEighty-three (83) RA patients (41 smokers, 42 have never smoked) were typed for HLA-DRB1* alleles by molecular techniques (PCR-SSOP and -SSP). In 62 out of 83 (74.7%) anti-CCP abs were detected by ELISA.ResultsIn RA pts and in comparison to the controls, increased frequency of HLA-DRB1*01:01 (28.9% vs 6.8%, OR=4.4), *10:01 (16.9% vs 2.4%, OR=8.4), *04:01 (3.6% vs 2%, OR=1.8), *04:04 (7.2% vs 1%, OR=7.6) and *04:05 (15.7% vs 3.7%, OR=4.8), as well as decreased frequency of *04:02 (1.2% vs 2%, OR=0.6) and *04:03 (4.8% vs 6.8%, OR=0.7) were found. Among the RA patients, 77.1% possess 1SE vs 18.9% of controls (OR=14.4), whereas 10.8% possess 2SE vs 1% of controls (OR=11.8). In CCP (+) RA patients and in comparison to CCP (-) an increased frequency of HLA-DRB1*01:01 (27.4% vs 14.3%, OR=2.3) and *10:01 (21% vs 4.8%, OR=5.3) was observed. Furthermore, 88.7% of CCP (+) carry 1SE vs 42.9% of CCP (-) patients (OR=10.5). CCP (+) smokers patients in comparison to CCP (+) non-smokers are presented with an increased frequency of DRB1*01:01 (41.9% vs 12.9%, OR=4.9). Among the CCP (+) smokers, 96.8% possess 1SE vs 80.6% of CCP (+) non-smokers (OR=7.2), whereas 12.9% possess 2SE vs 12.9% of CCP (+) non-smokers (OR=1).Conclusionsa) An increased frequency of HLA-DRB1*01:01, *10:01, *04:05 alleles, as well as the protective role of *04:02, *04:03 alleles in Greek patients with RA were confirmed b) The presence of any SE, particularly *10:01 allele, strongly influences the production of anti-CCP abs and c) Interaction between smoking and any SE, particularly *01:01 allele, is associated with anti-CCP positive RA in Greek patients.References Klareskog L, Stolt P, Lundberg K, Kallberg H, Bengtsson C, Grunewald J, et al. A new model for an etiology of rheumatoid arthritis: smoking may trigger HLA-DR (shared epitope)-restricted immune reactions to autoantigens modified by citrullination. Arthritis and rheumatism. 2006;54(1):38–46.Ioannidis JP, Tarassi K, Papadopoulos IA, Voulgari PV, Boki KA, Papasteriades CA, et al. Shared epitopes and rheumatoid arthritis: disease associations in Greece and meta-analysis of Mediterranean European populations. Seminars in arthritis and rheumatism. 2002;31(6):361–70.Lee YH, Bae SC, Song GG. Gene-environmental interaction between smoking and shared epitope on the development of anti-cyclic citrullinated peptide antibodies in rheumatoid arthritis: a meta-analysis. International journal of rheumatic diseases. 2014;17(5):528–35. Disclosure of InterestNone declared