Correlation of Antibodies against Nuclear Antigen using Immunofluorescence Pattern and Line Immunoassay Profile in Autoimmune Diseases at a Tertiary Care Hospital, Uttarakhand, India

Abstract

Introduction: Autoimmunity is a condition characterised by a specific humoral or cell-mediated immune response against constituents of the body’s own tissues. The diagnosis of autoimmune diseases (AD) is based on clinical presentation, laboratory diagnosis, and radiological diagnosis. Laboratory diagnosis involves the detection of antibodies directed against nuclear and cytoplasmic components of the cell. The gold standard test to detect antibodies against nuclear antigens is the Immunofluorescence Assay (IFA), which detects the presence of Antinuclear Antibody (ANA) in the serum. Other tests that can be used for ANA detection are Enzyme-Linked Immunosorbent Assay (ELISA), anti-Extractable Nuclear Antigen (anti-ENA), Line Immunoassay (LIA), etc. Aim: To correlate the results of antibodies against nuclear antigens based on various immunofluorescence patterns and LIA profiles in autoimmune disorders. Materials and Methods: The present study was a time- bound explorative and comparative cross-sectional study conducted at a teritary care hospital over a period of one year (December 2018 November 2019) in the Department of Medicine in collaboration with the Department of Microbiology, SGRR IM and HS, Dehradun, Uttrakhand, India. The study was carried out on a convenient sample. Out of a total of 178 subjects, 118 suspected cases were included in the study group, and 60 healthy individuals were included in the control group. ANA was detected by IFA using HEp-20-10/liver cell. All the samples that were positive or negative by IFA were further evaluated by LIA. The data obtained were statistically analysed for significance using Stastistical Packages of Social Sciences (SPSS) version 20.0. Results: The majority of cases in both groups belonged to the 30-50 year age group (69/118 in the study group and 37/60 in the control group). IFA was positive in 49.15% of the samples in the study group and 21.6% in the control group. The most common pattern observed in IFA was nuclear homogeneous. LIA was positive in 45.7% of the cases, with the maximum antibodies detected against dsDNA antigen (double-stranded DNA). In the study group, out of the 49% IFA-positive samples, 40.6% were also positive for antibodies by LIA, and an additional 5% of cases that were negative by IFA were found to be positive by LIA. The statistical strength of correlation between patterns in IFA and bands in LIA is established. Conclusion: A combination of IFA and LIA can serve as a better tool for early and accurate diagnosis of AD. In the control group, 25% were observed to be positive for ANA using both IFA and/ or LIA. Thus, there remains a possibility of such individuals developing ADs in the future.