Detection of anti-nuclear antibody by immunofluorescence assay and enzyme immunoassay in childhood systemic lupus erythematosus: experience from Bangladesh

Authors


Dr Tanjeem Rabika Dipti, Bangbandhu Sheikh Mujib Medical University, 355/2, Ahmed Nagar, Paikpara, Mirpur-01, Dhaka-1216, Bangladesh. Email: rtanjeem@yahoo.com

Abstract

Background:  Systemic lupus erythematosus (SLE) is a multisystem, chronic but often episodic, autoimmune disease that is characterized by the presence of antinuclear antibodies (ANA). The criteria set by American College of Rheumatology are widely used for diagnosis of SLE. Elevation of ANA titer is the most sensitive of the ACR criteria. There are different methods for detection of ANA. Indirect immunofluorescence (ANA-IFA) and enzyme immunoassay (ANA-EIA) are commonly used methods. The sensitivity of ANA-IFA using HEp-2 cell substrate is 90–100% in systemic rheumatic diseases. In Bangladesh most of the laboratories use ANA-EIA for detection of ANA. As the sensitivity of ANA-EIA is lower than ANA-IFA it might be that we are missing many cases of ANA positivity in childhood SLE cases.

Objectives:  To detect ANA by immunofluorescence assay using HEp-2 cell substrate and enzyme immunoassay in childhood SLE and to compare the diagnostic performance of these methods.

Material and methods:  This is a cross-sectional analytical study. A total of 40 patients were enrolled. Among them 20 were childhood SLE cases. Another 20 patients of childhood rheumatic diseases other than SLE were taken as the disease control group.

Result:  In childhood SLE cases, 100% were ANA-positive by IFA and 55% were ANA positive by EIA. The sensitivity of ANA-IFA was 100%. In contrast, sensitivity of ANA-EIA was 55%.

Conclusion:  ANA-IFA is superior to ANA-EIA for detection of ANA in childhood SLE patients. ANA-IFA should be the primary screening test for children with clinical features suggestive of SLE.

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