FRI0594 USE OF ANTI-DFS70 ANTIBODIES IN RHEUMATOLOGICAL PATIENTS WITH SUSPICION OF SYSTEMIC AUTOIMMUNE DISEASE
Authors: J. L. Tandaipan Jaime, B. Magallares, J. Bernardez, E. Riera Alonso, F. Pujalte, L. Martínez-Martínez, A. Baucells, I. Castellví, H. Corominas, S. Martinez Pardo
Journal: Annals of the Rheumatic Diseases (2020)

Background: Positivity of dense fine speckles antibodies (anti-DFS70) has been associated with antinuclear antibodies positivity in people with no evidence of systemic autoimmune disease. They could be useful to distinguish patients with these characteristics that do not meet diagnostic and/or classifying criteria for any systemic autoimmune disease (SAD). Objectives: To evaluate the use of anti- DFS70 in patients with suspicion of SAD. Methods: A cross-sectional observational study was conducted at 2 tertiary-level hospitals. We included a cohort of patients visited in the last year by either rheumatology or other specialties, under suspicion of SAD, in which the IgG isotype anti-DFS70 was obtained by recombination with the Euroline Immunoblot of Euroimmun. Demographic, clinical and immunological variables were collected. Results: 102 patients (78% women) were included, median age of 49 years old. The descriptive statistics are summarized in Table 1. All patients had ANA titters &gt; 1/80. 37% were positive for anti-DFS70, with homogeneous, speckled and other patterns in 36%, 72% and 15% respectively.74% were visited by rheumatologists under the suspicion of systemic lupus erythematosus (SLE) in 27%, other SAD 25%, arthralgia 36% and fibromyalgia 12%. 13% presented high DNA titters, low C3/C4 levels in 14% and 9%. SLE’s symptoms were: arthritis 21%, arthralgia 41%, cutaneous 20% and oral ulcers 8%. Anti-DFS70(+) was related to the speckled pattern in 46% compared to other patterns (p=0,009), which had a negative association with anti-DFS70(p=0,003). Regarding the diagnoses, there was a negative association with SLE, other SAD and other rheumatologic diagnoses in 88%, 75% and 55% respectively(p=0,006). Anti-DFS70(-) was associated with oral ulcers (p=0,024), decreased C3/C4 levels (p=0,007/p=0,018), psoriatic arthritis (p=0,024) and cutaneous lupus (p=0,008), but not with drug-induced SLE (p=0,48) or lupus nephritis (p=0,067). There was no statistical significance between anti-DFS70(+) and arthralgia or fibromyalgia, but these patients don’t have a SAD diagnosis. Table 1. RHEUMATOLOGY (n=75) OTHER SPECIALTIES (n=27) antiDFS70(+) n=25(100%) antiDFS70(-) n=50(100%) antiDFS70(+) n=13(100%) antiDFS70(-) n=14(100%) Women 20(80) 43(86) 8(62) 9(64) Age years (ED) 47,1 (±20,1) 50,4 (±15,5) 45,1(±26,7) 54,7(±15,6) ANA Homogeneous 8(32) 23(46) 2(15) 4(29) Pattern Speckled 22(88)* 30(60) 12(92) 9(64) IIF Other 0 10(20) 1(8) 4(29) Final diagnosis Arthralgia 12(48) 15(30) Speciality Fibromyalgia 3(12) 6(12) Dermatology 4(31) 7(49) Drug-induced SLE 2(8) 2(4) Gastroenterology 3(23) 3(21) SLE 3(12) 17(34)* Hematology 1(8) 2(14) Cutaneous lupus 0 8(16)* Other 5(38) 2(14) PsA 0 6(12)* Other 6(25) 16(32) SLE Arthritis 3(12) 13(26) Arthralgia 13(52) 18(36) Cutaneous 3(12) 12(24) Oral ulcers 0(0) 6(12)* Leukopenia 0(0) 4(8) Thrombocytopenia 0(0) 1(2) Fever 1(4) 1(2) Pleuritis 0(0) 1(2) Pericarditis 0(0) 1(2) Nephritis 0(0) 4(8) Myositis 1(4) 0(0) ANA (antinuclear antibody), IIF (indirect immunofluorescence), SLE (systemic lupus erythematosus), PsA (psoriatic arthritis), *p&lt;0, 05. Conclusion: Our results suggest that patients with suspicion of SAD, especially SLE, presented a greater proportion of negative anti-DFS70 compared to other diagnoses, including SAD, along with a decrease in complement levels and the presence of oral ulcers, being useful at the initial study of these patients. More studies are needed to characterize this association. Disclosure of Interests: Jose Luis TANDAIPAN JAIME: None declared, Berta Magallares: None declared, Julia Bernardez: None declared, ELENA RIERA ALONSO: None declared, FRANCISCO PUJALTE: None declared, Laura Martínez-Martínez: None declared, ANDRES BAUCELLS: None declared, Ivan Castellví Consultant of: Boehringer Ingelheim, Actelion, Kern Pharma, Speakers bureau: Boehringer Ingelheim, Actelion, Bristol-Myers Squibb, Roche, Hector Corominas: None declared, Silvia Martinez Pardo: None declared