Determination of anti-ds-DNA antibody levels in patients with systemic lupus erythematosus by Elisa, RIA and crithidia methods: Changes in antibodies prior to disease activity

ABSTRACT

Antibodies [Abs] to double-stranded [ds] DNA have been considered most useful in diagnosis and monitoring disease activity in patients with systemic lupus erythematosus [SLE]. To investigate the value of anti-ds-DNA Ab level changes, detected by three different methods, as predictor of disease activity in SLE patients. Serial sampling from 87 patients with SLE was performed. Samples were assessed for anti-ds-DNA Abs by Crithidia luciliae test [CLT], ELISA and Farr assay. In 17 out of 40 cases with completed sampling, disease activity was occurred during the study. Significant increases in anti-ds-DNA Ab level was detected by ELISA [whole and IgG] and Farr assay prior to disease activity in all clinically active patients. CLT was tested positive in only one case before disease activity. None of the 23 cases with clinically inactive disease were tested positive with CLT, whereas in 3 and 15 of 23 cases positive results were observed by ELISA and Farr assay, respectively. Statistical analysis showed the predictive value of ELISA for disease activity. There was a high correlation between the results of Farr assay and ELISA for all SLE patients in detecting anti-ds-DNA Abs [r=0.63, p<0.0001]. ELISA and Farr assay were also correlated well with disease activity [p<0.05]. Our findings confirm the predictive value of increases in anti-ds-DNA Abs measured by ELISA method with respect to activity of SLE