CD4+ T Cells from Healthy Subjects and Colon Cancer Patients Recognize a Carcinoembryonic Antigen-specific Immunodominant Epitope

Gabriele Campi, Mariacristina Crosti, Giuseppe Consogno, Valeria Facchinetti, Bianca M. Conti-Fine, Renato Longhi, Giulia Casorati, Paolo Dellabona, Maria Pia Protti

Research output: Contribution to journalArticle

Abstract

The carcinoembryonic antigen (CEA) is an attractive target for immunotherapeutic purposes because of its expression profile, its role in tumor progression, and its immunogenicity. However, CEA belongs to the CD66 immunoglobulin super-gene family that comprises highly homologous molecules expressed on leukocytes, making CEA a potential autoantigen expressed on hematopoietic cells. We used a MHC class II epitope prediction algorithm (TEPITOPE) to select 11 sequence segments of CEA that could form promiscuous CD4+ T-cell epitopes and used synthetic peptides corresponding to the predicted sequences to propagate in vitro CD4+ T cells from healthy donors and colon cancer patients. CD4+ T cells from all subjects strongly recognized the sequence segment (LWWVN-NQSLPVSP), repeated at residues 177-189 and 355-367. Importantly, we demonstrated that this highly immunodominant region contains a naturally processed epitope(s). Cross-recognition experiments with peptide analogues present on the CD66 homologous proteins showed that CEA177-189/355-367-specific CD4 + T cells did not recognize the analogues, demonstrating that recognition of the immunodominant epitope is CEA specific. These data suggest that the repertoire of CEA177-189/355-367-specific CD4+ T cells might have been shaped by a selective process to exclude CD4+ T cells specific for CD66 homologues expressed on leukocyte, while preserving the CEA-specific repertoire. The features of strong immunogenicity and immunodominance in the absence of potential induction of autoimmunity make the identified CEA epitope of particular interest for the development of antitumor vaccines.

Original languageEnglish
Pages (from-to)8481-8486
Number of pages6
JournalCancer Research
Volume63
Issue number23
Publication statusPublished - Dec 1 2003

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ASJC Scopus subject areas

  • Cancer Research
  • Oncology

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