Evaluation of ELISA and indirect immunofluorescence in the diagnosis of autoimmune diseases and their interpretation in the clinical situation

Abstract

Introduction: Systemic autoimmune diseases include conditions where the immune system fails to recognize self antigens leading to production of auto antibodies and subsequent damage to several organs and tissue systems, e.g., Systemic lupus erythematosus, Scleroderma or Systemic sclerosis, Dermatomyosits, Polyarteritis nodosa and Mixed connective tissue disease. Detection of antinuclear antibodies (ANA) has been found to be the single most important criteria for the diagnosis of connective tissue disorders. Materials and Methods: The commonly used methods to detect ANA like ELISA and indirect immunofluorescence (IFA) were evaluated in this study. Results: ELISA showed a sensitivity, specificity, positive predictive value, negative predictive value, false positive rate and false negative rate of 93%, 54%, 60%, 92%, 45% and 7% respectively when compared to IFA. Conclusions: ELISA is non-specific and less useful as a diagnostic test whereas ANA IFA is a more accurate test and the gold standard.