In physiology, the activation and clonal expansion of antigen-specific T cells are essential events for the successful generation of adaptive immune responses. T-cell activation is initiated by specific molecular interactions between the T cell receptor (TCR)-CD3 complex on T cells and the antigenic peptide presented by major histocompatibility complex (MHC) molecules on the surface of either antigen presenting cells (APCs) or target cells. Additionally, the presence of costimulatory and immune checkpoint inhibitors on APCs or target cells determines the quality and quantity of T cell activation and the subsequent fate of the T cell clone.

Spanning from routine laboratory studies on T cell biology to manufacturing processes involved in T cell adoptive therapies (e.g. tumor-infiltrating lymphocytes (TIL) and chimeric antigen receptor (CAR) T cells), proper activation of the T cells is critically necessary. This Methods Collection aims to bring together the conventional and novel methods of T cell activation, as well as the relevant techniques to characterize the consequences of each activation method. For example, T cell activation and expansion using soluble reagents, commercially available products, natural and artificial APCs, bioreactors, and novel scaffold platforms are highly anticipated. Various characterization techniques such as flow cytometry, microscopy, and cell counting methods should be supplemented to examine and monitor the quantity and quality of each T cell activation method.