[Detection of anti-ENA and anti-dsDNA antibodies using line immunoassay in systemic autoimmune diseases].
BACKGROUND
Detection of antibodies to extractable nuclear antigens (ENAs) and dsDNA is needed for the diagnosis of and predicting prognosis in systemic autoimmune diseases. Recently introduced line immunoassay (LIA) has the advantage of detecting several autoantibodies simultaneously, and we evaluated its usefulness in the diagnosis of autoimmune diseases in comparison with enzyme-linked immunosorbent assay (ELISA).


METHODS
Samples were collected from 437 patients referred by rheumatologists. FANA (fluorescent antinuclear antibody) test and LIA for the detection of 13 different autoantibodies, including 6 ENAs and dsDNA were performed. LIA-positive samples for ENA or dsDNA antibodies were further tested with ELISA. Final diagnosis was made by rheumatologists according to the diagnostic criteria. Agreement of results between LIA and ELISA was analyzed in 53 selected patients with systemic autoimmune diseases.


RESULTS
The LIA detected antibodies to ENA and dsDNA in 118 and 22 patients, respectively, and ELISA detected 70.3% (83/118) and 45.5% (10/22) of LIA positive samples. Especially, 60.2% (71/118) of patients with positive ENA antibody on LIA was diagnosed as systemic autoimmune diseases. Patients having strong FANA titer and homogenous/speckled pattern showed higher prevalence of autoantibodies, but a small proportion of FANA negative patients also showed positive reactivity (LIA 10.8%, ELISA 5.2%). LIA showed a good agreement with ELISA for the anti-ENA antibodies (> or =80%), and a lower agreement for the anti-dsDNA antibody (67.9%).


CONCLUSIONS
LIA detecting several autoantibodies simultaneously might replace ELISA for anti-ENA antibodies, but not for anti-dsDNA antibodies. When LIA is performed considering clinical manifestations and FANA, it could contribute to the diagnosis of systemic autoimmune disease.
Kim
Ji Myung
JM
Department of Laboratory Medicine, Eulji University Hospital, Daejeon, Korea. jmkim@eulji.ac.kr
Ihm
Chun Hwa
CH
Sin
Dong Hyuk
DH
Ihm
Mi Kyung
MK
Sim
Seung Chul
SC
D000974:Antibodies, Antinuclear / Q000032:analysis*; D034961:Antigens, Nuclear / Q000276:immunology; D001327:Autoimmune Diseases / Q000175:diagnosis*; D004247:DNA / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D007118:Immunoassay; D008297:Male; D008875:Middle Aged; D011933:Reagent Kits, Diagnostic; D015203:Reproducibility of Results
D000974:Antibodies, Antinuclear; D034961:Antigens, Nuclear; D011933:Reagent Kits, Diagnostic; D004247:DNA