In situ detection of antigen-specific tumor-infiltrating lymphocytes using newly designed tetramers.

We described a new process for the design of HLA tetramers using soluble MHC class I molecules purified from Epstein Barr Virus-transformed B cells. This method does not rely on genetic engineering and presents a significant advantage in view of the polymorphism of MHC class I molecules because tetramers can be produced with any HLA molecule. Here, we showed that our HLA-A∗0201 tetramers provided experimental results similar to those obtained with tetramers made with recombinant MHC molecules. Moreover, they can be used to efficiently identify peptide-specific T cells from ex vivo PBMCs as well as from lymphocytes infiltrating human tumor. This innovative and simple method could be widely adopted, specially in diagnostic procedures for monitoring peptide-based immunotherapy.