Determination of antinuclear antibodies by immunoblotting to clarify the immunological characteristics of patients with systemic lupus erythematosus and Sjogren's syndrome
Authors:   PhD in Medicine, Senior Researcher at the Laboratory of Methods for the Treatment and Prevention of Joint Diseases of FSBI Zborovsky Research Institute of Clinical and Experimental Rheumatology, Akhverdyan Yu.R. , Papichev E.V. ,   PhD in Medicine, Researcher at the Laboratory for Methods of Treatment and Prevention of Joint Diseases of FSBI Zborovsky Research Institute of Clinical and Experimental Rheumatology, Zavodovsky B.V. ,   Doctor of Medical Sciences, the head of the laboratory of methods of treatment and prevention of joint diseases of FSBI Zborovsky Research Institute of Clinical and Experimental Rheumatology, Polyakova Yu.V. ,   PhD in Medicine, Researcher of FSBI Zborovsky Research Institute of Clinical and Experimental Rheumatology, Sivordova L.E. ,   PhD in Medicine, leading researcher at the laboratory of methods for the treatment and prevention of joint diseases of FSBI Zborovsky Research Institute of Clinical and Experimental Rheumatology
Published: January 2025

Objective: to study the immunological characteristics of patients with systemic lupus erythematosus and Sjogren's syndrome by determining antinuclear antibodies using immunoblotting.
Materials and methods. We observed 69 patients whose average age was 38.9 years [23.2-62.9], of which 63 (91.30%) were women and 6 (8.69%) men. BMI was 27.3 kg/m2 [21.8-49.2]. Inclusion criteria: age from 18 to 70 years, presence of a reliable diagnosis. To study the diagnostic value of determining the ANA profile, patients were divided into 3 groups: 1st group – 15 patients with systemic lupus erythematosus (SLE), 2nd – 21 patients with the disease and Sjögren’s syndrome (SS), 3rd (control) group – 33 patients with osteoarthritis. The control group was comparable to the study groups by gender and age.
Results. The determination of anti-SS-A in SLE has good quality (area under the ROC curve - 0.66). A cut-off value was determined with 79.6% specificity and 53.3% sensitivity. Anti-RNP/SM, anti-Sm, anti-dsDNA and anti-HI were somewhat less sensitive (30%), with a specificity level of 91% for anti-dsDNA and anti-Sm and 100% for anti-RNP/Sm and anti -HI. The most informative diagnostic tests for the disease and Sjogren's syndrome are anti-Ro-52 recombinant (sensitivity 57.1%, specificity 96%), anti-SS-Anative (sensitivity 52.4%, specificity 86%). The determination of anti-Ro-52 in SS is of good quality, which confirms the value of the area under the ROC curve (>0.7). The optimal cut-off value corresponded to 99.6% specificity and 57.1% sensitivity. Somewhat less sensitive (28.6%) were anti-Sm (specificity - 92%), anti-dsDNA (specificity - 92%) and anti-RIB (specificity 100.0%).
Findings. The laboratory tests studied, as a rule, had high specificity, but rather low sensitivity. The most specific tests for diagnosing SLE are antibodies to the antigens RNP/Sm, SS-Anative, antibodies to histones, for SS - anti-SS-Anative, anti-Ro-52 recombinant, anti-RIB.
Keywords: systemic lupus erythematosus, Sjögren's syndrome, immunoblotting, antinuclear antibodies.