Background:Connective tissue disorders (CTDs) are a group of autoimmune diseases characterized by the presence of circulating antinuclear antibodies (ANA), which serve as critical biomarkers for early diagnosis. Indirect immunofluorescence (IIF) on HEp-2 cells remains the gold standard for ANA detection and enables interpretation of distinct fluorescence patterns that are often disease-specific.

Objective:To evaluate the seroprevalence of ANA and to analyze the distribution and clinical significance of fluorescence patterns observed by IIF in patients clinically suspected of CTDs.

Methods:A cross-sectional study was conducted over a five-month period involving 90 patients with clinical suspicion of CTDs. Serum samples were tested for ANA using a commercial HEp-2 IIF assay at a screening dilution of 1:80. Positive samples were further categorized based on fluorescence patterns, and the results were analyzed in relation to age, gender, and probable clinical diagnosis.

Results:Of the 90 samples tested, 59 (65.6%) were positive for ANA. ANA positivity was significantly higher in females (73%) compared to males (48%) (p < 0.05). The most common fluorescence pattern was speckled (35.6%), followed by homogenous (27.1%), nucleolar (15.2%), peripheral (10.1%), centromere (6.8%), and cytoplasmic (5.1%). The homogenous pattern was primarily associated with suspected systemic lupus erythematosus, while nucleolar and centromere patterns were linked with systemic sclerosis. ANA positivity was highest in the 31–50 years age group.

Conclusion:IIF remains a highly sensitive and informative method for ANA detection in suspected CTD patients. The interpretation of fluorescence patterns provides valuable diagnostic clues and aids in the clinical stratification of autoimmune diseases. These findings support the continued use of IIF as a frontline serological tool in the diagnostic workup of CTDs.