What is the difference between the different T cell types?

Cytotoxic T lymphocytes (CTLs) are the “classical” T cells – the ones responsible for identifying and inducing apoptosis in infected and tumor cells. They’re assisted by T helper cells (Th), which produce a bevy of immunoactivating cytokines (e.g., interleukins and interferons) to boost macrophage activity and CTL proliferation. In contrast, regulatory T cells (Treg) are immunosuppressive, and diminish T cell activity by secreting immunosuppressive cytokines, inducing T cell apoptosis, and blocking naïve T cell activation. Their function is vital to preventing the development of autoimmune disorders. Finally, memory T cells (Tmem) are T cells which have been primed for a specific antigen but did not mature into effector cells during that instance. Instead, they retain their specificity for that antigen, but remain inactive until a second encounter, at which point they activate a much faster and more potent immune response relative to the first encounter.1,2 For an expanded view on this topic please visit our resource center for information on CAR-T cells.

1. C.A. Janeway Jr., et al., Immunobiology: The Immune System in Health and Disease. 6th edition. New York: Garland Science; 2005.
2. V. Golubovskaya and L. Wu. “Different Subsets of T Cells, Memory, Effector Functions, and CAR-T Immunotherapy”, Cancers (Basel) 8(3): 36, 2016.