White blood cells, of which T cells are a subset, are essential to the adaptive immune system. Based on the exact role they play, they fall into one of two categories: MHC class I-restricted CD8-expressing T cells (CD8), also referred to as cytotoxic T lymphocytes, and MHC class II-restricted CD4-expressing T cells (CD4), which can develop into distinct T helper subtypes. T cells participate in a range of immunological responses that emerge in different diseases, such as cancer, autoimmune disorders, allergy diseases, and infections. T cells in cancer develop malfunction as a result of ongoing exposure to antigens. After being stimulated by an antigen, naive T cells quickly become activated and undergo effector T cell differentiation. Reprogramming of transcription, epigenetics, and metabolism is required for effector T cell development.
