The essential elements of adaptive immunity and their relevance to cancer immunology

The adaptive immune system has unique qualities that set immunotherapeutic approaches to cancer apart from conventional and targeted therapies. The antigen receptors expressed by T cells and B cells are highly specific and sufficiently sensitive to be able to discern single amino acid alterations in protein sequences presented by dendritic cells or tumors. Tumoricidal cytolytic and cytokine production by activated T cells is localized and targeted. Activated lymphocytes undergo varied differentiation steps, regulated by transcriptional and metabolic alterations, that either augment their effector activities or result in the generation of memory cell populations that are poised to respond to recurrent disease. Homing receptors direct the trafficking and localization of tumor-specific lymphocytes. The development of contemporary immunotherapies, from cancer vaccines to immunomodulatory antibodies and chimeric antigen receptor (CAR)-T and transgenic T cells, has been dependent on a careful dissection and understanding of the basic biology of each of these components.