膀胱癌BCG免疫療法患者におけるBCG 65kDa蛋白抗原に対する免疫応答

Abstract

The BCG 65 kDa protein is part of the 60 kDa heat-shock protein (hsp) family. It is clear that hsp has a huge homology among mammalian and bacterial cells. In our study, we have observed the relevance of this protein in the anti-tumor response. Antibody production against the BCG 65 kDa protein was determined by solid phase ELISA using the sera of 51 bladder cancer patients who have undergone BCG instillation therapy. The BCG 65 kDa protein was made by E. coli transfected with pTB12 (plasmid DNA) which encodes this protein. It was clearly observed that the level of serum antibody titer to this protein was raised by the above instillation therapy. In order to investigate the role of this protein in anti-tumor response, we developed monoclonal antibodies against BCG 65 kDa protein. Four monoclonal antibodies were developed (B-20, B-97, B-108, B-167). We also estimated the epitope defined by each monoclonal antibody by using the truncated protein which was produced by E. coli transfected with the deletion mutants of pTB12. At this stage, we proceeded with observation of the cross epitope between mammalian cancer cells and BCG after using these monoclonal antibodies. There is no cross epitope defined by B-20, B-97 and B-167 in mammalian cells. However, the epitope defined by B-108 exists in normal tissue as well as in bladder cancer cells.