Ex vivo analysis of tumor antigen specific CD8(+) T cell responses using MHC/peptide tetramers in cancer patients

The development of soluble tetrameric MHC/peptide complexes has opened the possibility to directly identify and monitor antigen-specific CD8(+) T cell s in different clinical situations. This represents a technological breakth rough for the field of cell-mediated immunity, For example, the direct iden tification and enumeration of tumor-specific CD8(+) T cells at the rumor si te and in blood has recently provided compelling evidence that strong anti- tumoral responses naturally occur in some cancer patients. Moreover, the us e of tetramers plays an essential role in the design of vaccination protoco ls aimed at inducing a strong and protective CD8(+) T cell-mediated anti-tu moral response in cancer patients. The monitoring of antigen-specific T cel l responses elicited by various peptide-based vaccines tested in phase I cl inical trials clearly indicates that tumor-specific CD8(+) T cells can be a ctivated effectively at least in some cancer patients. Thus. multiparameter monitoring of antigen-specific T cell responses that combines ex vivo tetr amer staining with various phenotyping and functional assays provides a nov el approach to assess the functional potential of tumor-specific T lymphocy tes and may also facilitate the optimization of vaccination protocols. (C) 2001 Elsevier Science B.V. All rights reserved.