Antibodies Expressed by Intratumoral B Cells as the Basis for a Diagnostic Test for Lung Cancer

We used a novel method to discover tumor antigens with the intent to develop a diagnostic assay for lung cancer. We isolated intratumoral B lymphocytes ITLs, cloned their immunoglobulin genes, and used the expressed antibodies to identify tumor antigens. All of the antibodies produced from ITLs in our study were polyreactive. One antibody that preferentially recognized tropomyosin 4 was identified this antibody was confirmed in the serum of the same cancer patient, and in a small pilot study, the tropomyosin 4 antibody was found to be specific for the diagnosis of lung cancer, but was not very sensitive 20. We are currently modifying our approach to identify those ITLs that show evidence of clonal expansion prior to the cloning and expression of recombinant antibodies. This will increase the likelihood that the recombinant antibodies produced are the result of proliferation and differentiation in response to tumor antigens. This will allow us to concentrate our cloning, antigen identification, and validation efforts on those antibodies that are more likely to demonstrate high affinity monoreactivity against tumor antigens. Isolation of single ITLs and cloning of their immunoglobulin genes has the potential to be a useful approach for identifying diagnostic biomarkers or novel molecular targets.