Antibodies to native DNA in discoid lupus erythematosus

Phototesting and photoprotection in LE

Photosensitivity and induction of skin lesions following UV radiation is a common problem of patients with cutaneous and systemic forms of lupus erythematosus. The detrimental effect of UV radiation to patients with lupus erythematosus was already recognized in the last century. Skin lesions can now be provoked under standardized conditions allowing the diagnosis and classification of patients with photosensitive disorders. The aim of this review is to give an overview on the history, test procedure and test results in patients with lupus erythematosus.

Antinuclear antibody profiles in relation to specific disease manifestations of systemic lupus erythematosus

The aim of the study was to investigate the prevalence of antinuclear and associated antibodies (anti-dsDNA, anticardiolipin, anti-RNP, anti-Sm, anti-SSA and anti-SSB) and/or combinations thereof in systemic lupus erythematosus (SLE) patients with respect to their diagnostic and pathogenetic significance. The prevalence of anti-dsDNA antibodies was strongly influenced by the selection criteria of the patient; the lowest prevalence was found in SLE patients with central nervous system (CNS) involvement; the highest prevalence in patients with nephritis. The results were also influenced by the different assays. Combinding different assays (Farr/PEG ratio) quantitative as well as qualitative differences could be shown between patients with nephritis (Farr/PEG ratio greater than or equal to 5) and with CNS involvement (Farr/PEG ratio less than 5). No difference in anticardiolipin antibody prevalence between the different SLE patient groups could be demonstrated. Regarding antibodies against RNP, Sm, SSA and SSB, the prevalence was found to be strongly influenced by the criteria used for patient selection. Only in CNS patients and association with anti-RNP and anti-SSB antibodies alone or in combination was found. In pleuropericarditis a weak association with RNP antibodies existed.

IN CONCLUSION

studying the prevalence and possible pathogenetic significance of antibodies one should always consider patient selection criteria and the effect of the different assays used when analysing the results.

Serologic and clinical features of patients with discoid lupus erythematosus: relationship of antibodies to single-stranded deoxyribonucleic acid and of other antinuclear antibody subsets to clinical manifestations

Serologic and clinical data were obtained from forty patients with discoid lupus erythematosus in 1982. Clinical disease was characterized by quality, extent, severity, activity, photosensitivity, and systemic manifestations. The patient's sera were examined for the presence of antinuclear, anti-Ro and anti-La, anti-ribonucleoprotein and anti-Sm, anti-single-stranded deoxyribonucleic acid (ssDNA), and antinative DNA antibodies. In late 1984, thirty-three patients had follow-up clinical examinations. On the initial evaluation the patients with positive antinuclear antibody (ANA) findings were clinically characterized by a significantly higher incidence of photosensitivity and arthritis, an elevated erythrocyte sedimentation rate, and cutaneous lesions of subacute cutaneous lupus erythematosus. The activity and extent of disease in 1982 did not correlate with the presence of ANA. Elevated levels of ssDNA antibodies were present in seven of the forty patients (significantly greater than control subjects; (p less than 0.005) and correlated with widespread, active discoid lupus erythematosus, an elevated erythrocyte sedimentation rate, and a slightly greater risk of systemic lupus erythematosus in 1982. At the 2-year follow-up examination, thirteen of the seventeen patients with a positive ANA had active clinical cutaneous disease, and ten of the sixteen patients with negative ANA findings had continued activity (not statistically significant). However, all seven patients with elevated ssDNA antibody levels had continued activity, and disease progression had occurred in three. Thus the presence of ssDNA seems to correlate strongly with active, progressive lupus erythematosus. The presence of antibody abnormalities in patients with discoid lupus erythematosus correlates with clinical disease and provides more support for the theory linking discoid lupus erythematosus to systemic lupus erythematosus as part of a continuum.

Antibodies to native DNA and serum complement (C3) levels. Application to diagnosis and classification of systemic lupus erythematosus

The sensitivity and specificity of the presence of antibodies to native DNA and low serum C3 levels were investigated in a prospective study in 98 patients with systemic lupus erythematosus who were followed for a mean of 38.4 months. Hospitalized patients, patients with other connective tissue diseases, and subjects without any disease served as the control group. Seventy-two percent of the patients with systemic lupus erythematosus had a high DNA-binding value (more than 33 percent) initially, and an additional 20 percent had a high DNA-binding value later in the course of the illness. Similarly, C3 levels were low (less than 81 mg/100 ml) in 38 percent of the patients with systemic lupus erythematosus initially and in 66 percent of the patients at any time during the study. High DNA-binding and low C3 levels each showed extremely high predictive value (94 percent) for the diagnosis of systemic lupus erythematosus when applied in a patient population in which that diagnosis was considered. The presence of both abnormalities was 100 percent correct in predicting the diagnosis os systemic lupus erythematosus. Both tests should be included in future criteria for the diagnosis and classification of systemic lupus erythematosus.

Prognostic value of anti-dsDNA in SLE

In a prospective longitudinal study 130 patients with systemic lupus erythematosus (SLE) were studied at least monthly for a relationship between the anti-dsDNA levels and disease activity. We observed 13 patients who developed 15 periods of exacerbations of their disease. All 15 exacerbations were preceded by a continuous increase of the anti-dsDNA levels. In 13 of the 15 exacerbations studied the exacerbation was preceded by an increase of anti-dsDNA with a doubling time (T2) of less than 6 weeks; in 4 of the 5 other exacerbations the T2 was less than 10 weeks. Four other patients with an increase of the anti-dsDNA levels showed no exacerbation. In these 4 patients the T2 was larger than 10 weeks. The other 113 patients did not show an increase of anti-dsDNA over the 2 years of monitoring and showed no signs of serious disease activity (no major symptoms). These observations suggest that an SLE patient who is followed up frequently and who shows a continuous increase of anti-dsDNA witha T2 shorter than 10 weeks is bound to develop an exacerbation.

Antibodies to single-stranded DNA in patients with discoid lupus erythematosus

Sera from 31 patients with discoid lupus erythematosus were examined for the presence of antibodies to single-stranded and native DNA. None of these sera had antibodies to native DNA. When rabbit anti-human IgM was used, 6 of 28 patients had elevated binding, whereas only 1 of 29 patients had abnormal binding when antiIgG was used. The IgM nature of this response was confirmed when we demonstrated the binding activity in heavy fractions from gel filtration. We concluded that at least one-fifth of patients with discoid lupus erythematosus have IgM antibodies to single-stranded DNA.

Detection of anti-dsDNA as diagnostic tool

The diagnostic significance of anti-dsDNA determinations was evaluated in 2 different groups of patients. When the immunofluorescence technique (IFT) with Crithidia luciliae and the Farr assay with 3H-labelled-PM2 DNA were applied to a selected panel of 536 sera from patients with various well-defined autoimmune diseases, positive results were obtained only with serum samples from patients with systemic lupus erythematosus (SLE). On the other hand when we screened 4431 sera sent to our laboratory for diagnostic reasons, we observed a high incidence of antibodies to dsDNA in patients who did not fulfil the preliminary American Rheumatism Association's criteria for SLE and did not have the diagnosis SLE. Furthermore, a significant number of the positive sera showed peculiar behaviour in that they were positive only in the IFT on Crithidia luciliae and not in the Farr assay.

Analysis of DNA structure by hydroxyapatite columns and ethidium bromide fluorescence techniques. A comparative study and effect on DNA binding

Seven duplex DNA preparations have been structurally analyzed by hydroxyapatite column chromatography and an ethidium bromide fluorescence technique. Significant contamination of one preparation with single-stranded DNA was detected by hydroxyapatite column chromatography. Five of the other six preparations were found to contain significant single-stranded regions by the ethidium bromide fluorescence technique. Synthetic poly dAT was found to be duplex in structure. The presence of single-stranded regions considerably influenced DNA binding results in a radioimmunoassay.

Antibodies to cytoplasmic antigens in lupus erythematosus. Serologic marker for systemic disease

Seven patients with classic cutaneous lupus erythematosus are described. Three of these patients had features satisfying four of the American Rheumatism Association (ARA) preliminary criteria for the diagnosis of systemic lupus erythematosus (SLE). Their sera, however, lacked antinuclear antibodies but demonstrated precipitating antibodies reactive against cytoplasmic RNP (La) and non-nucleic acid (Ro) antigens. Four additional ANA-negative patients lacking significant skin disease but having a lupus-like multisystem disease were found to have antibodies to soluble cytoplasmic antigens. Thirty-three of 130 ANA-positive SLE patients, but none of 16 discoid lupus patients, possessed these anticytoplasmic antibodies. These findings suggest that antibodies to Ro and La may be a marker for systemic disease in ANA-negative patients with 1) cutaneous lupus and 2) a distinct subpopulation of patients with a lupus-like syndrome without skin disease.

Antibodies to UV DNA and photosensitivity

Antibodies to ultraviolet light denatured DNA (UV DNA) have been measured in the sera of patients with systemic lupus erythematosus, discoid lupus erythematosus, and light sensitive skin lesions. Antibodies were found in significant levels in the patients with SLE but not in the other groups. It appears that although UV denaturation of dermal DNA occurs in vivo this is not sufficient to induce antibodies to UV DNA in patients with a normal DNA repair mechanism. This may not be the case in patients with SLE in whom a break in tolerance to Native (N-) DNA has already occurred and where antibody to N-DNA will cross react with UV DNA.

Correlation between levels of DNA antibodies and clinical disease activity in SLE

Sera were tested from 23 patients with systemic lupus erythematosus followed over a period of 1 to 5 years. Antibodies to native DNA were measured and correlated retrospectively with clinical evidence of disease activity. The overall degree of correlation between the presence of DNA antibodies and evidence of disease activity was good (P less than 0-001). Of 206 sera tested, only 4 had a normal DNA antibody at a time when significant clinical activity was noted. In contrast, 34 sera had mild to moderately raised DNA antibody levels at times of clinical remission. Although DNA antibodies are a useful investigation in the monitoring of disease activity, changes in therapy should not necessarily be made on DNA antibody levels alone.

Pathways of complement activation in chronic discoid lupus: serologic and immunofluorescence studies

To assess the relative roles of the classic and alternative pathways of complement activation in chronic discoid lupus erythematosus (CDLE), serum levels of properdin, C3, and C4, and deposition of these proteins in the dermal-epidermal junction (DEJ) of 20 CDLE patients were compared to the findings in patients with clinically active and inactive SLE. Properdin was demonstrated in the DEJ of 10 of 14 (71%) histologically typical skin lesions from patients with CDLE, usually in association with deposits of immunoglobulin, C3, and C4. Properdin levels in CDLE patients were significantly increased (137 +/- 34%) (P less than 0.05) when compared to normal controls (101 +/- 18%) or to patients with clinically active SLE (89 +/- 32%). C3, C4, DNA-binding, and antinuclear antibody tests in CDLE were indistinguishable from those in normals, but significantly different from patients with active SLE (P less than 0.05). The complement profiles of patients with clinically inactive SLE resembled those of CDLE patients more closely than those of active SLE patients.

Double-stranded RNA antibodies in systemic lupus erythematosus

Antibodies to viral double-stranded RNA (ds RNA) have been found in 40% of patients with systemic lupus erythematosus (SLE) and 14-5% of patients with rheumatoid arthritis. These antibodies were diagnostically more specific SLE than those directed against artificial polynucleotides, poly I:C and poly A:U. Although not disease specific, high titres of antibody to ds viral RNA were found almost exclusively in SLE. Serial studies failed to show that RNA antibody levels correlated with disease activity. Although of considerable interest in experimental studies on the pathogenesis of SLE, ds viral RNA antibodies are of little clinical significance in the management of SLE.