Introduction

Vaccination strategies for the treatment of human cancer depend on the existence of tumour antigens which are able to elicit specific immune responses in the tumour-bearing host. The specific recognition of antigens by the immune system is accomplished by two targeting systems: CD4+ and CD8+ T lymphocytes recognize processed antigens presented on MHC class II and class I molecules, respectively, while B lymphocytes produce antibody molecules that bind specifically to unprocessed antigens. The analysis of humoral and cellular immune responses in cancer patients had indicated for a long time that cancer-specific antigens do indeed exist and are recognized by the immune system of the tumour-bearing host. However, the molecular nature of these antigens remained unclear until cloning techniques were developed that used established cytotoxic T lymphocyte (CTL) clones or circulating antibodies as probes for screening of tumour-derived expression libraries. The CTL approach and the antigens identified by it are reviewed elsewhere in this book (Chapter 11). This chapter is intended to give an introduction to the serological approach, to summarize the current status of antigens identified and to provide a perspective for the use of these antigens for cancer immunotherapy.

Rationale for using the antibody repertoire of cancer patients for the identification of tumour antigens

A variety of in vitro studies and animal tumour models demonstrated that CTLs are the protagonists of an effective cytotoxic antitumoural immune response and motivated the search for antigens recognized by CD8+ T lymphocytes.