Journal zyxwvutsrqpon of zyxwvutsrqponmlkjih Iiiiniuriorlier.apy zyxwvutsrqponm 21(3): zyxwvutsrqponmlk 198-204 zyxwvutsrqpo 0 1998 Lippincott-Raven Publishers, Philadelphia Third Keystone Symposium on Cellular Immunology and the Immunotherapy of Cancer T Cell Response to Tumors Intralesional Selection of T Cell Clonotypes in the Immune Response to Melanoma Antigens Occurring During Vaccination Marialuisa Sensi, Cinthia Farina, Cristina Maccalli, Andrea Anichini, *David Berd, and Giorgio Parmiani Division of Experimental Oizcology D, Istituto Nazionale Turnori, Milan, Italy; and *Thoinas Jefferson University, Philadelphia, Pennsylvania, U.S.A. Summary: T cells infiltrating pre- and postvaccine metastases obtained from mela- noma patients vaccinated with either dinitrophenyl (DNP)-modified autologous tumor or with the MACE-3.Al peptide display selective T cell receptor (TCR) zyxw p chain variable region (BV) repertoire changes at the tumor site as a consequence of vacci- nation. Restricted sets of BV families expand in all postvaccine lesions when compared with prevaccine specimens and often contain dominant clones. A protocol devised to obtain T cell lines highly enriched for expression of a given BV region through the use of anti-BV monoclonal antibodies was used to understand whether responses to spe- cific antigen(s) accounted for these clonal expansions. In one of the patients vaccinated with DNP-modified tumor cells, BV-driven selection of the T lymphocytes expanded in two infiltrated postvaccine metastases resulted in T cell lines able to exert HLA class I-restricted lysis of the autologous tumor. These results indicate that TCR repertoire analysis at the tumor site facilitates the detection of T cell responses elicited by a vaccine and potentially cytotoxic for the autologous tumor. Key Words: Vaccina- tion-T cell receptor-Melanoma antigens-Cytotoxic T lymphocytes-Human. The recent progress in the molecular characterization of tumor antigens and in the identification of the peptides presented by given major histocompatibility complex (MHC) molecules to cytotoxic T cells paved the way to the development of a series of peptide-based vaccination strategies (1-3). In addition, the possibility to immunize against still unidentified tumor antigens supports the clinical use of autologous tumor tissue as a vaccine. Given the established role of cytotoxic T lymphocytes Address correspondence and reprint requests to Dr. M. Sensi at Division of Experimental Oncology D, Istituto Nazionale Tumori, Via Venezian 1, 20133 Milan, Italy. (CTLs) in recognition and killing of tumor cells in vitro and in mediating long-term therapeutic responses in ex- perimental animals, the ability to induce CTL responses in peripheral blood has been taken as the main parameter to monitor the effect of a given vaccine (4-6). Whether or not an immune response occurs in situ and is specifi- cally directed to the antigens used for vaccination and expressed by the tumor cells has been rarely addressed. A peptide-specific HLA-A 1 -restricted CTL response has been recently detected both at the tumor site and in pe- ripheral blood lymphocytes (PBLs) in a patient vacci- nated with MAGE- 1 peptide-pulsed autologous antigen- presenting cells (5). PeptideMHC complex recognition zy 198