Similar frequency of autoantibodies against 70‐kD class heat‐shock proteins in healthy subjects and systemic lupus erythematosus patients
Stress or heat‐shock proteins may be involved in the initiation and perpetuation of autoimmune diseases. In order to investigate a possible role of autoantibodies against the 70‐kD family of heat‐shock proteins in systemic lupus erythematosus (SLE), sera of SLE patients and healthy subjects were tested for the presence of IgG and IgM antibodies to 70‐kD class proteins. These proteins were purified by affinity chromatography on ATP‐agarose and used in Western blotting studies. The data obtained revealed that antibodies to the 72‐kD and the 73‐kD heat‐shock proteins occurred with similar frequencies both in healthy subjects and SLE patients. Thus, approximately 20% of the sera in each group contained IgG antibodies, and IgM antibodies were detected in about 30% of the sera tested. Moreover, in SLE patients no association between the occurrence and litre of these antibodies and disease activity was found. These data suggest that antibodies to the 70‐kD class heat‐shock proteins are naturally occurring and argue therefore against an involvement of these antibodies in the pathogenesis of SLE.