Antinuclear Antibodies Profiling in Patients with Autoimmune Diseases: A Cross-sectional Study from Tertiary Care Centre in Southern India

Introduction: Over past few decades, autoimmune disorders have been increasing in India but adequate research on it hasn’t been done yet. Antinuclear antibodies (ANA) serve as one of the most important hallmarks of autoimmunity. Recent studies and research are focusing on demonstrating the correlation between the wide range of ANA and various autoimmune disorders. Aim: To profile ANA and correlate their patterns with clinical manifestations in patients with autoimmune diseases at a Tertiary Care Centre in South India. Materials and Methods: The present cross-sectional study was carried out for 12 months (from February 2023 to January 2024) at SRM Medical College Hospital and Research Centre, Kattankulathur, Chennai, Tamil Nadu, India. Patients presenting with rheumatic symptoms and referred for ANA testing using the Indirect Immunofluorescence (IIF) method were included in the study. The study population comprised both male and female participants, with age groups ranging from paediatrics to geriatrics. A total of 526 blood samples (3-5 mL) were collected from patients with rheumatic complaints and processed to obtain serum. IIF was performed using the Mosaic HEp-20-10/ Liver (Monkey) BIOCHIP kit to detect ANA patterns. Positive samples (n=67) were further evaluated using EUROLINE ANA Profile 3 Plus DFS70 IgG immunoblot for specific autoantibodies, and the results were correlated with the clinical diagnosis of autoimmune disorders. The collected data were analysed using IBM Statistical Package for Social Sciences (SPSS) Statistics software. Descriptive statistics and inferential tests such as the Chi-square test was applied. A p-value of <0.05 was considered statistically significant. Results: A total of 526 patients were investigated for ANA testing. A total of 67 samples positive for IIF-ANA were further tested using the immunoblot method. Out of the 67 samples processed/tested for presence of the human antibodies specific to 16 nuclear, mitochondrial and cytoplasmic antigens, 55 (82%) samples showed positivity. Out of the 67 samples, 49 (73.13%) were female and a significant number of the patients were in the age groups 31-40 (16, 23.8%) and 41-50 years (16, 23.8%). Speckled pattern was most frequently observed 21 (31.3%). The majorly identified autoantibodies were against U1RNP 18 (26.8%) and nucleosomes 18 (26.8%). Conclusion: A higher- ANA pattern positivity could be correlated with a high prevalence of autoimmunity in this geographical location, promoting its use as a means for detecting suspected autoimmune illnesses.