T cell activation and antigen presentation process

T cell activation and antigen presentation is a multi-step cellular process essential to the adaptive immune response. Antigen-presenting cells (APCs) such as dendritic cells, macrophages, and B cells, process and display antigenic peptides via major histocompatibility complex (MHC) molecules. T cells, through their T cell receptor (TCR), recognize these peptide-MHC complexes, receiving a first activation signal. A second, co-stimulatory signal (e.g., via CD28 on T cells binding to B7 molecules on APCs) is required for full T cell activation. Successful activation leads to T cell proliferation, differentiation, and execution of immune functions, such as cytotoxic killing or cytokine secretion. This process is central to immunotherapies (e.g., checkpoint inhibitors targeting CTLA-4 or PD-1) and is implicated in multiple diseases, including infections, cancer, and autoimmune disorders.

Other names

T-lymphocyte activationTCR signaling and antigen presentationimmune synapse formation