Clinical Significance of Antibodies to DFS70 in Immunoinflammatory Rheumatic Diseases.

The relevance of the problem of immunoinflammatory rheumatic diseases (IIRD) for modern medicine is determined by their high prevalence in the population, the difficulty of early diagnosis, the rapid development of disability and poor life prognosis. Recent data on the significance of anti-DFS70 have opened up new possibilities for optimizing the step-by-step diagnosis of IIRD. The detection of these antibodies can help in the interpretation of a positive result for antinuclear antibodies (ANA) by indirect immunofluorescence assay on HEp-2 cells (IIFA-HEp-2) in the absence of autoantibodies specific for IIRD. Detection of anti-DFS70 in antinuclear factor (ANF) seropositive patients without clinical and/or serological markers characteristic of a certain disease from the IIRD group can be considered as a potential marker that excludes this group of diseases.

[Modern look at the problems of investigation of antinuclear antibodies in systemic lupus erythematosus (literature review).]

In the review, topical aspects of the study of antinuclear antibodies (ANA) in systemic lupus erythematosus (SLE) are considered. ANA is the main serological marker of SLE. In the sera of patients with SLE, antibodies to DNA, histones, nucleosomes, extractable nuclear antigens (Sm, U1 ribonucleoprotein, Ro / SSA, La / SSB, ribosomal protein P), nucleolar antigens and other cellular structures are detected. The ANA study using indirect immunofluorescence on HEp-2 cells (IIF-HEp-2) is recommended as a standard screening test for the diagnosis of SLE. The use of automated systems for the interpretation of cellular fluorescent tests contributes to the standardization and improvement of the reproducibility of the IIF. A new international nomenclature of types of nuclear, nucleolar (nucleolar), cytoplasmic and mitotic luminescence of ANA in IIF-HEp-2, including 28 variants of anticell ("Anti-cell" - AC) patterns was developed. In the practice of clinical diagnostic laboratories, high-performance automated methods for the determination of ANA based on ELISA, immunoblot, fluorescent, chemiluminescent and multiplex immunoassay are widely used. New mono- and multiplex methods of solid-phase analysis are expediently used as confirmatory reflex tests for the detection of varieties of antigen-specific ANA in patients with SLE with positive results of IIF-HEp-2. Identification of ANA profiles using multiplex technologies is a useful tool for implementing a personalized approach to diagnosis, evaluation of activity, prognosis, clinical and immunological subtypes, and the effectiveness of SLE therapy. The need for an ANA study not only to confirm the diagnosis of SLE, but also to identify the disease in the early and preclinical stages with the intention to prevent the development of the pathological process is discussed. Detection of monospecific anti-DFS70 antibodies allows to exclude the diagnosis of SLE inANA IIF-HEp-2 positive subjects. Presented is a modern algorithm for testing ANA with SLE.

[Clinical value of multiplex immune assay of antinuclear antibodies in systemic lupus erythematosus.]

A promising trend in the diagnosis of systemic autoimmune diseases is the multiplex immune assay (MIA) of autoantibodies and other laboratory biomarkers using microchips. The aim of the work was to study the diagnostic and prognostic significance of MIA antinuclear antibody (ANA) profiles in systemic lupus erythematosus (SLE). 94 patients with SLE, 70 patients with other rheumatic diseases and 30 healthy donors were examined. ANA (antibodies to doublestranded - dsDNA, Sm, SS-A/Ro, SS-B/La antigens, nucleosomes, ribosomal protein P-RibP and ribonucleoprotein - RNP-70) were determined in the serum by MIA using the xMAP technology. In MIA, antibodies to dsDNA, Sm and RibP have a high diagnostic specificity (Sp) (95.0-99.0%) and a likelihood ratio of positive results (LR+) (9.67-15.0), i.e. are the most "useful" diagnostic tests, and antibodies to RNP-70, SS-A/Ro and nucleosomes are classified as "useful" tests for the diagnosis of SLE (Sp: 84.0-95.0%, LR+> 2.0). Determination of profiles from 3 or more antigen-specific ANA by MIA increases the Sp method to 98.0-100%, and the LR+ - to the maximum values. Profiles from 7 subpopulations of ANA (antibodies to dsDNA, Sm, RibP, SS-A/Ro,SS-B/La, nucleosomes and RNP-70, 57.9%, 71.9%, 82.5%, 61.4 %, 84.2%, 50.9%, 84.2%) were found in the chronic variant of SLE. In the acute course of the disease, 4 subpopulations of ANA are simultaneously detected (antibodies to dsDNA, Sm, SS-A/Ro and nucleosomes, 77.3%, 45.5%, 40.9% and 72.7%); in subacute course there are 2 subpopulations of ANA (antibodies to dsDNA and nucleosomes, 53.3% and 46.7%). The activity index of SLEDAI-2K positively correlates with the concentration of antibodies to dsDNA (r = 0.55, p < 0.05), nucleosomes (r = 0.65, p < 0.05), RibP (r = 0.32; p < 0.05) and Sm (r = 0.36, p < 0.05) in the blood. There was no reliable relationship between the production of varieties of ANA and the index of organ damage. Mucocutaneous disorders, lupus-nephritis and neurolupus were most often associated with the detection of antibodies to dsDNA (53.2-64.0%), nucleosomes (55.3-66.0%), SS-A/Ro (38.0-40.4%) and Sm (27.8-36.2%). MIA of ANA profiles is an important tool for implementing a personalized approach to diagnosis, evaluation of activity, course and clinical and immunologic subtypes of SLE.

[THE CLINICAL INFORMATIVENESS OF AUTOMATED METHODS OF SCREENING DETECTION OF ANTI-NUCLEAR ANTIBODIES USING INDIRECT REACTION OF IMMUNE FLUORESCENCE, ENZYME-LINKED IMMUNOSORBENT ASSAY AND MULTIPLEX XMAP TECHNOLOGY UNDER SYSTEMIC LUPUS ERYTHEMATOSUS].

Thew antinuclear antibodies (ANA) consist heterogeneous group of auto antibodies reacting with various components of nucleus and cytoplasm. The ANA is a main serological marker of systemic lupus erythematosus (SLE). The implementation in clinical practice of new highly productive techniques of immune analysis using automated systems sets up prerequisites for standardization and amelioration of reproducibility of detection of ANA. The study was carried out to compare diagnostic significance of automated techniques of screening detection of ANA (indirect immunofluorescence test on cells HEp-2 (IIFT-HEp-2)), enzyme-linked immunosorbent assay (ELISA) and multi-complex immune analysis (MIA, using suspension technology xMAP) in serum of patients with SLE. The serums from 94 patients with SLE were analyzed. The comparison group included 70 patients with other rheumatic diseases. The control group consisted of 30 healthy donors. The screening detection of ANA using technique IIFT-HEp-2 was implemented on automated platform AKLIDES, ELISA - on automated analyzer ALEGRIA and MIA on automated analyzer BioPlex 2200. The technique IIFT-HEp-2 demonstrated the most high diagnostic sensitivity as compared with ELISA and MIA- BioPlex 2200 (96.8%; 79.8% and 82.9% correspondingly). The general diagnostic specificity of detection of ANA using technique IIFT-HEp-2 was lower than in case of ELISA and MIO-BioPlex 2200 (40%, 70% and 57% correspondingly). In the group of healthy donors the lowest diagnostic specificity was observed in ANA screening analysis using MIA-BioPlex 2200 (80%) while in case of applying IIFT-HEp-2 and ELISA indices of diagnostic specificity made up 93.3% and 96.7% correspondingly. The ANA analysis of mix of 26 nuclear antigens using ELISA technique was a reliable laboratory test for diagnostic of SLE (likelihood ratio of positive result - 2.66). By the level of likelihood ratio of negative result of the IIFT-HEp-2 technique was more informative test for exclusion of diagnosis of SLE than techniques of ELISA and MIA-BioPlex 2200 (0.08; 0.29 and 0.3 correspondingly). The detection of ANA using technique of is the most preferable primary screening test for diagnostic of SLE. The ELISA of antibodies to mix of nuclear antigens and MIA on the basis of xMAP technology are less preferable screening tests for diagnostic of SLE as compared with IIFT-HEp-2 because of false-negative results in 20% and 17% of cases correspondingly. ELISA and MIA are to applied as confirmatory screening tests permitting to detect antigen-specific ANA in patients with SLE with positive results of IIFT-HEp-2.