The clinical significance of autoantibodies to soluble cellular antigens in systemic lupus erythematosus.

The relationships between autoantibodies to soluble cellular antigens and clinical features in systemic lupus erythematosus (SLE) were investigated in a large clinical-serological study. The absence of these precipitins in serum was associated with a low prevalence of vasculitis and membranous nephropathy (MGN). Other significant findings were the associations between nRNP antibody and Raynaud's phenomenon and MGN, SSB antibody and sicca complex, PCNA antibody and a young age at onset, and Bu antibody and an old age at onset. However, the most impressive findings were in DA1-positive patients which showed a unique prevalence of photosensitive skin lesions, lymphoadenopathy and hepatosplenomegaly. The present study confirms the usefulness of antibodies to soluble cellular antigens in the classification of patients with SLE.

Relationship between antibodies to dsDNA and to soluble cellular antigens and histologically defined glomerulonephritis in patients with SLE.

To better define the relationships between circulating autoantibodies and renal involvement in systemic lupus erythematosus (SLE), antibodies to both dsDNA and soluble cellular antigens were detected in sera from a large series of SLE patients. Significantly higher dsDNA binding activities and lower complement levels at onset were found in patients with renal disease; however, this was uniquely due to subjects with diffuse or focal proliferative glomerulonephritis. Patients with membranous nephropathy (MGN) showed very low dsDNA binding activities (6/9 of them being negative for dsDNA antibodies) and normal mean C3 and C4 levels. A comparison between patients with proliferative nephritis and patients without renal involvement with high dsDNA binding activities revealed significantly lower complement levels in the former group. No significant difference was observed in the prevalence of antibodies to soluble cellular antigens between patients with or without renal disease; however, nRNP antibody was two-fold more frequent in patients with MGN than in all other subgroups. This study highlights the close relationship between concurrently high anti-dsDNA and low complement levels and proliferative glomerulonephritis in SLE, and suggests that subjects with MGN may represent a subgroup of SLE patients showing peculiar serological features. Different mechanisms possibly involved in the pathogenesis of MGN in SLE are discussed.

Detection of two associated precipitating autoantibodies (DA1 and DA2) in sera from patients with systemic lupus erythematosus.

In a clinical and serological study performed on a large series of patients with different connective tissue disorders, only sera from patients with systemic lupus erythematosus (SLE) contained two precipitin systems (DA1 and DA2) directed against nuclear proteins present in a total extract of human spleen. DA1 antibody appeared in 5% of SLE patients and was always associated with DA2 antibody which was found in about 22% of SLE patients. Sera monospecific for DA1 and DA2 antibodies gave a speckled staining pattern on both rat kidney and HEp2 cells. DA1-positive patients showed a higher incidence of photosensitivity (p less than 0.001), hepatosplenomegaly (p less than 0.001), hemolytic anemia (p less than 0.05), CNS involvement, vasculitis, and diffuse proliferative glomerulonephritis than DA1-negative ones. DA2-positive patients showed an increased incidence of leukopenia (p less than 0.05) and thrombocytopenia (p less than 0.01) than controls. While several indirect evidences suggest that DA1 precipitin might be identical to the previously described MA antibody, DA2 precipitin appears as a new system in SLE. The serological association between DA1 and DA2 antibodies might be analogous to the well known ones between antibodies to Sm and nRNP and to SSA/Ro and SSB/La.

Clinical findings in patients with SLE whose sera contain antibodies to ribosomal ribonucleoprotein.

In a clinical and serological study performed on a large series of patients with different connective tissue diseases, anti-ribosomal ribonucleoprotein (rRNP) antibodies were detected only in a small proportion of sera with systemic lupus erythematosus (SLE). SLE patients positive for anti-rRNP autoantibodies showed a significantly higher incidence of hemolytic anemia. The reasons for this surprising association are still unclear; however, this finding suggests that rRNP precipitin might be considered as a useful marker of a particular subgroup of patients with SLE.

Comparison between counterimmunoelectrophoresis and double radial immunodiffusion in the detection of antibodies to topoisomerase I in sera from scleroderma patients.

Sera from 146 patients with progressive systemic sclerosis have been submitted to the detection of anti-Scl 70 antibodies by both double radial immunodiffusion (ID) and counterimmunoelectrophoresis (CIE). CIE detected a significantly higher number of positive sera from patients with diffuse scleroderma, while no difference between the two techniques was noted in sera from patients with CREST variant. CIE increases the diagnostic importance of the serologic investigation in systemic sclerosis and gains a better distinction between subgroups of patients with different clinical expressions of this disease.

Anti-Epstein-Barr virus antibodies in systemic lupus erythematosus.

Sera from 18 patients with Systemic Lupus Erythematosus (SLE), 20 with nonA-nonB acute hepatitis and 19 healthy subjects were tested for the presence of antibodies to the viral capside of Epstein-Barr virus. In patients with SLE the mean titre of anti-VCA IgG was significantly higher than in normal subjects (p less than 0.02), and the percentage of patients with titres greater than 1:160 was significantly higher than in normal population (p less than 0.01). These high anti-VCA) titres in SLE patients are probably related to a defective immune surveillance.

Antibodies to Epstein-Barr virus and cytomegalovirus in primary Sjogren's syndrome.

Sera from 28 patients with Primary Sjögren's Syndrome (SS) and 20 healthy subjects were tested for the presence of antibodies to Epstein-Barr Virus (EBV) and Cytomegalovirus (CMV). No difference was noted in the mean titre of anti-CMV antibodies in patients and in controls. For what concerns EBV, the mean titre of anti-EBNA antibodies was significantly higher in SS patients than in normals (p less than 0.001); moreover, within the SS population, titres were higher in SSB-positive than in SSB-negative patients (p less than 0.05). These results, together with the fact that anti-SSB antibodies (characteristic of Sjögren's Syndrome) recognize also two EBV-encoded RNAs, strengthen the hypothesis that EBV is involved in the pathogenesis of SS.

Autoantibody to proliferating cell nuclear antigen (PCNA) in SLE: a clinical and serological study.

In a clinical and serological follow-up study on a large series of subjects with different connective tissue disorders, anti-PCNA/cyclin autoantibodies were found in about 3% of patients with SLE. Positive subjects showed a higher incidence of diffuse proliferative glomerulonephritis and hematological disorders than the general SLE population. A highly significant serological association between PCNA and SL/Ki autoantibodies (p less than 0.001) has been observed. Persistence or disappearance of serum PCNA antibodies were independent of any clinical and serological feature or the therapeutic regimen employed.