RESUMO
We describe new autoantibodies which recognize two cytoplasmic proteins of 30 and 26 kDa. They were detected by Western blot analysis in the sera of 6 of 79 randomly selected systemic lupus erithematosus (SLE) patients and are denoted anti-JA antibodies. This antibody specificity is different from the previously described lupus autoantibodies, anti-P and anti-S10. The targeted autoantigens are trypsin sensitive, and resistant to RNase and DNase treatment. The binding to the antigens was not modified when reticulocyte ribosomes were prepared with protease inhibitors indicating that these are primary antigen and not degradation products. Several lines of evidence suggest that these proteins are almost certainly part of the ribosome. Anti-JA reactivity was not observed in the sera from 60 patients with other autoimmune diseases or from normal individulas. In contrast, 55% of lupus sera selected for a high titer of anti-ds DNA (double stranded DNA) and LE cells were also anti-JA positive. Anti-JA antibodies may be useful as a specific serological marker for disease activity in SLE. The strong association with anbti-ds-DNA antibodies and LE cell in the sera of SLE patients requires further study