Results of the anti-C-reactive protein autoantibody (anti-CRP) analyses. Twenty of 50 systemic lupus erythematosus (SLE) sera were positive; 7 of 10 patients were positive on at least one occasion. Positive samples are indicated by filled circles, negative samples by open circles. The positive control (SLE reference) sample was defined as 100%. All samples below 0% were considered negative.