Clinical evaluation of a modified ELISA, using photobiotinylated DNA, for the detection of anti-DNA antibodies.
The measurement of anti-dsDNA antibodies is important for the diagnosis and the follow-up of patients with systemic lupus erythematosus (SLE). For routine detection of anti-dsDNA, the Farr assay and the immunofluorescence technique (IFT) on Crithidia luciliae proved to be very useful. The anti-dsDNA ELISA is not used for routine purposes in our institute since it is flawed by false-positive results due to binding of negatively charged (immune) complexes to the employed precoat (protamine sulphate). Recently, a new anti-dsDNA ELISA has been described in which photobiotinylated dsDNA is coated to streptavidin coated plates. To investigate whether this modified ELISA is more specific than the classical anti-dsDNA ELISA, we tested sera of patients with SLE (n = 51), myasthenia gravis (MG, n = 25), rheumatoid arthritis (RA, n = 25) and Sjögren's syndrome (SS, n = 23) and sera of healthy blood bank donors (BBD, n = 25). In both assays the sera of the SLE patients gave significantly higher values than the sera of healthy blood bank donors. In the classical ELISA, 84% of the sera from patients with RA and 28% of sera of patients with MG were found positive. For the modified assay the figures were 8% and 24%, respectively. This modified ELISA was further studied and clinically evaluated by comparing it with the classical anti-DNA ELISA and two other anti-DNA assays (Farr assay and IFT), using 500 sera sent to our institute for routine anti-DNA determination and sera of an additional 75 healthy blood bank donors. Quantitatively, both ELISAs showed the same high degree of correlation with the IFT. The modified ELISA gave a better correlation with the Farr assay than the classical anti-DNA ELISA. From our data we conclude that the ELISA using photobiotinylated DNA is a more reliable assay than the classical anti-DNA ELISA.
Hylkema
M N
MN
Department of Autoimmune Diseases, The Netherlands Red Cross Blood Transfusion Service (C.L.B.), Amsterdam.
Huygen
H
H
Kramers
C
C
vd Wal
T J
TJ
de Jong
J
J
van Bruggen
M C
MC
Swaak
A J
AJ
Berden
J H
JH
Smeenk
R J
RJ
D000974:Antibodies, Antinuclear / Q000032:analysis*; D001327:Autoimmune Diseases / Q000276:immunology*; D001710:Biotin; D004247:DNA / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005069:Evaluation Studies as Topic; D005455:Fluorescent Antibody Technique; D006801:Humans; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D000974:Antibodies, Antinuclear; D001710:Biotin; D004247:DNA