Further observations on the precipitation test for diagnosis of systemic lupus erythematosus.

Abstract

In a recent report dealing with an evaluation of the precipitation test of Jones and Thompson for the diagnosis of systemic lupus erythematosus, we observed that the beta globulin fraction of a serum contained some component that caused a false-positive reaction to occur when that serum was treated with p-toluene sulfonic acid. I t was definitely determined that the patient from whom the serum was taken did not have systemic lupus erythematosus. Friou,' in adapting immunologic studies of Masouredis to the study of lupus erythematosus (L.E.), has contended that the site of the lupus erythematosus antibody factor is in the gamma globulin fraction of the serum. Because our initial observation was based on findings from only 1 serum that yielded a false-positive L.E. precipitation test, we extended our project to include electrophoretic studies on the other 22 serums that also yielded false-positive reactions. In this way we hoped to determine whether or not there were protein fractions other than the beta globulin which might be associated with the false-positive reaction.