T Cell Antigen Recognition and Discrimination by Electrochemiluminescence Imaging

Adoptive T lymphocyte (T cell) transfer and tumour‐specific peptide vaccines are innovative cancer therapies. An accurate assessment of the specific reactivity of T cell receptors (TCRs) to tumour antigens is required because of the high heterogeneity of tumour cells and the immunosuppressive tumour microenvironment. In this study, we report a label‐free electrochemiluminescence (ECL) imaging approach for recognising and discriminating between TCRs and tumour‐specific antigens by imaging the immune synapses of T cells. Various T cell stimuli, including agonistic antibodies, auxiliary molecules, and tumour‐specific antigens, were modified on the electrode's surface to allow for their interaction with T cells bearing different TCRs. The formation of immune synapses activated by specific stimuli produced a negative (shadow) ECL image, from which T cell antigen recognition and discrimination were evaluated by analysing the spreading area and the recognition intensity of T cells. This approach provides an easy way to assess TCR‐antigen specificity and screen both of them for immunotherapies. We report a label‐free approach for imaging immune synapses of T cells by electrochemiluminescence microscopy, which allows us to discriminate specific T cell receptor (TCR)/peptide‐loaded major histocompatibility complex (pMHC) recognition, as well as the role of auxiliary molecules (costimulatory and adhesion molecules). The results would be useful in the development of tumour vaccines and adoptive T cell transfer immunotherapy.