Autoantibodies in systemic lupus erythematosus and normal subjects

Abstract

The presence of various antibodies in serum samples from patients with systemic lupus erythematosus (SLE) and from healthy subjects was investigated by ELISA, using a panel of natural antigens. Fifty-eight serum samples from 58 healthy women and 50 serum samples from 30 patients with active SLE were tested with 9 natural antigens (ds-DNA, actin, tubulin, thyroglobulin, myosin, myoglobin, human transferrin, human interferon a and BSA FV). It was found that the proportion of positive sera from healthy women at a dilution of 1/20 was almost the same as that of lupus sera at a dilution of 1/150 for nearly all antigens, while at a dilution of 1/150 the proportion of positive sera from patients with SLE was significantly higher for nearly all antigens. In lupus sera a high degree of correlation was observed between titers of anti-DNA and titers of the other antibodies. One hundred eighty-eight serum samples from 53 SLE patients, taken during exacerbation and remission of the disease were tested with ds-DNA, actin and tubulin. Antibodies (IgG) to ds-DNA actin and tubulin were found in the majority of serum samples taken during the active phase of the disease. On the other hand, very few serum samples taken during remission were found to be positive. A high degree of correlation was found between the OD of anti-actin/anti-ds-DNA (r=0.769) and anti-tubulin/anti-ds-DNA (r=0.829). In a competitive enzyme immunoassay for DNA, actin, tubulin, myosin and thyroglobulin, a high degree of inhibition was observed with the homologous antigens. Cross inhibition was observed between actin, tubulin and myosin, and to a lesser degree with DNA. These results indicate that normal sera contain low titers of auto and foreign antibodies while active SLE sera react strongly with the same antigens.