Autoantibody to heat shock protein Hsp40 in sera of lung cancer patients

Heat shock protein Hsp40 is a stress protein with chaperone activity and ha s a cooperative function with Hsp70 in mammalian tells. We examined the pos sible expression of Hsp40 in Lung tumor tissues using immunoblotting and im munohistochemistry, and established an enzyme-linked immunosorbent assay (E LISA) method to detect IgG antibody to Hsp40 in the serum using purified hu man Hsp40. Sera were obtained from 130 normal subjects and 50 patients with lung cancer lung tumor tissues and cells specifically overexpressed Hsp40, and no such expression was detected in normal lung tissues. Compared with normal sera, significantly higher levels of auto-antibody to Hsp40 were pre sent in patients with lung cancer. The present study is the first to demons trate overexpression of Hsp40 in human tumor tissue and the associated pres ence of autoantibody to Hsp40 in the serum. These results suggest that over expression of Hsp40 in tumor cells may be recognized as a self-antigen.