Since denatured DNA (d-DNA) is trapped to membrane filter by itself, the millipore filter assay, frequently used to detect antibodies to native DNA (n-DNA), has been thought to be unsuitable to disclose the antibodies to d-DNA. Application of sonication to the heat-denatured 14C-DNA obtained from E. Coli, however, prevented the direct attachment of d-DNA antigen to the filter membrane, and made it possible to measure the d-DNA binding activities of sera by millipore filter method. The optimal sonication time was 15 second at 2.5A using KUBOTA INSONATOR Model 200M. To avoid the nonspecific bindings between the 14C-d-DNA and sera, 0.1 molar of borate buffer (pH 8.3) was used throughout the study. All of the sera with active SLE and 64% of patients with inactive SLE revealed high d-DNA binding activities. Some of sera with inactive SLE, however, had high-grade d-DNA binding activities without any to n-DNA. In the group of other rheumatic diseases, several sera of dermatomyositis and Sjogren's syndrome had relatively high binding activities monospecific to d-DNA. In a group of sera with SLE, the correlations between the severity of lupus nephritis and the difference of reactivity to n-DNA and d-DNA were studied. In sera of patients with active lupus nephritis, high-grade binding activities to n-DNA and relatively lowgrade d-DNA bindings were detected. In contrast, the sera of patients with inactive lupus nephritis had low n-DNA binding activities and relatively high d-DNA bindings. The difference of reactivity to DNA in these two groups were statistically significant (P<0.02). These data suggest that d-DNA anti-d-DNA antibody system have less pathogenetic roles in developing active lupus nephritis.
|Number of pages||1|
|Publication status||Published - Jan 1 1978|
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