Comparative analysis of linear antibody epitopes on human and mycobacterial 60-kDa heat shock proteins using samples of healthy blood donors.

Growing evidence suggests that anti-Hsp60 antibodies might be involved in the pathogenesis of different autoimmune diseases. Attempts were reported also on the characterization of epitope specificity of anti-Hsp60 antibodies in different infectious and autoimmune diseases. However, there is a lack of data on the occurrence and epitope specificity of anti-Hsp60 antibodies in the healthy human antibody repertoire. Therefore, the aim of our study was to demonstrate the presence of anti-Hsp60 antibodies and to investigate the epitope specificity of these antibodies using a large set of synthetic 10 mer peptides covering regions of Hsp60 with high probability of antigenicity. Here we report the identification of several linear epitopes using serum Ig (IVIG) and sera from healthy subjects by ELISA assay. We have identified two epitopes 'specific' for human Hsp60 and two different epitopes 'specific' for Hsp65. In addition, six epitopes were cross-reactive in nature, detected on both proteins. The presence of these 'specific' epitopes may explain the differences in epitope structure between Hsp60 and Hsp65 observed earlier in patients with cardiovascular disease. The binding of the IVIG preparation to Hsp60 epitopes might indicate that anti-Hsp60 autoantibodies are present in the healthy human natural autoantibody repertoire.