High sensitive detection of double-stranded DNA autoantibodies by a modified Crithidia luciliae immunofluorescence test.
Anti-double-stranded (ds)DNA antibodies are serological markers of systemic lupus erythematosus (SLE). Of all anti-dsDNA antibody detection methods, the Crithidia luciliae immunofluorescence test (CLIFT) is thought to have the highest specificity for SLE. However, the clinical application is hampered by the low diagnostic sensitivity. A CLIFT with modified assay buffer (mCLIFT) was developed and compared with conventional CLIFT, using sera from 110 patients with SLE, 89 anti-dsDNA ELISA-positive patients with other diseases (non-SLE group A), 157 non-SLE patients with undetectable anti-dsDNA antibodies by ELISA (non-SLE group B), 77 disease controls (non-SLE group C), and 50 healthy blood donors. Out of the 110 anti-dsDNA antibody ELISA-positive SLE patients, 84 (76.4%) demonstrated a positive kinetoplast staining, using the mCLIFT, compared to only 42.3%, using the conventional CLIFT. The diagnostic specificity of mCLIFT was 100% with healthy blood donors and 98.1% with the non-SLE group C (anti-nuclear antibodies negative; no signs or symptoms of an autoimmune disease) included. In the non-SLE groups A and B with various other autoimmune diseases or symptoms of a possible autoimmune disease, positive mCLIFT results were obtained in 33.7% and 3.2%, respectively. In conclusion, by modification of the assay buffer, a significant increase in sensitivity of the CLIFT could be observed while retaining the high specificity for SLE. Further investigation is required to check whether the CLIFT-positive non-SLE patients develop SLE and whether anti-dsDNA antibodies detected by the mCLIFT represent a pathogenetic and diagnostic subgroup of autoantibodies that may improve the early diagnosis of SLE or SLE-overlap syndromes.
Conrad
Karsten
K
Technical University Dresden, Institute of Immunology, Dresden, Germany. k_conrad@mail.zih.tu-dresden.de
Ittenson
Annelore
A
Reinhold
Dirk
D
Fischer
Richard
R
Roggenbuck
Dirk
D
Büttner
Thomas
T
Bosselmann
Hans-Peter
HP
Steinbach
Jörg
J
Schössler
Werner
W
D000818:Animals; D000974:Antibodies, Antinuclear / Q000097:blood*; D000953:Antigens, Protozoan / Q000276:immunology; D003421:Crithidia / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005455:Fluorescent Antibody Technique / Q000379:methods*; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000175:diagnosis*; D008856:Microscopy, Fluorescence; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D000974:Antibodies, Antinuclear; D000953:Antigens, Protozoan