Presence of antibodies to replication protein A in some patients with systemic lupus erythematosus (SLE)

Presence of antibodies directed against replication protein A (RPA), a DNA binding protein complex composed of three subunits (RPA-70, RPA-32 and RPA-14) was investigated among patients with SLE and other autoimmune diseases using immunoblot analysis to RPA-70 and RPA-32 recombinant proteins. Anti-RPA antibodies were found in two out of 108 sera from SLE patients, one of them showing reactivity against RPA-32 and RPA-70 and the other reacting only against RPA-32. Sera from 108 patients with other autoimmune disorders as well as from 42 healthy control individuals were negative. Thus, the frequency of these antibodies in SLE is estimated to be 2-3%. The study demonstrates that RPA is one target more of the wide array of autoantigens that elicit an immune response in SLE. The presence of anti-RPA autoantibodies seems to be circumscribed to a small number of patients with SLE.