Generation of scFv from a Phage Display Mini-Library Derived from Tumor-Infiltrating B-Cells

B lymphocytes that infiltrate solid tumors, known as tumor-infiltrating lymphocyte B-cells (TIL-B-cells), are present in human tumors from different histological types (1 ,2 ) and tumor-specific antibodies can be detected in many cancer patients. For instance, anti-idiotypic antibodies have been derived from patients with B lymphoma (3 ) and anti-neuroblastoma antibodies have been detected in some neuroblastoma patients (4 ). In most cases, these antibodies are characterized as auto-antibodies binding to self intracellular proteins. Some of these antibodies, such as anti-p53 antibodies, could be used as markers of relapsing tumors, of tumors not yet detected, or even as effector molecules in adjuvant immunotherapy (5 ,6 ). However, the analysis of the repertoire and of the specificity of antibodies present in cancer patients has been limited by considerable technical difficulties. Traditional methods such as hybridoma technology or Epstein Barr Virus (EBV) transformation of B-cells introduce an important selection bias due to their low efficacy. They allow B-cell lines to be generated which are highly unstable and poor immunoglobulin (Ig) producers. However, molecular engineering now makes it possible to study the antibody repertoire in great detail and to derive human recombinant antibody fragments. The random combination of cloned heavy- and light-chain variable regions (VH and VL) and their expression as single-chain Fv (scFv) or Fab fragments on the surface of bacteriophages (7 –9 ) is a powerful method (termed “phage display”) to study and select antibodies in patients with different diseases.