Tissue-resident lymphocytes: from adaptive to innate immunity

Area of Science:

• Immunology
• Cell Biology

Background:

• Immune responses rely on innate and adaptive immune cell coordination.
• Previously, CD8+ memory T cells and natural killer (NK) cells were thought to constantly recirculate.
• Recent advancements revealed noncirculating, tissue-resident populations of these cells.

Purpose of the Study:

• To review recent findings on tissue residency of lymphocytes.
• To focus on CD8+ T_RM cells, unconventional T cells, and emerging trNK cells.
• To discuss their phenotypes, functions, and roles in anti-viral and anti-tumor immunity.

Main Methods:

• Review of recent scientific literature.
• Analysis of immunological techniques enabling identification of tissue-resident cells.
• Comparative analysis of phenotypes and functions of resident vs. circulating lymphocytes.

Main Results:

• Discovery of tissue-resident memory T (T_RM) cells in diverse peripheral organs and secondary lymphoid organs (SLOs).
• Identification of tissue-resident NK (trNK) cells in various tissues like uterus, skin, and kidney.
• Characterization of unique phenotypes and non-recirculating nature of these resident lymphocytes.

Conclusions:

• The understanding of immune cell distribution has evolved, including T_RM and trNK cells.
• Tissue-resident lymphocytes exhibit distinct characteristics and functions.
• These cells hold significant implications for developing novel anti-viral and anti-tumor immunotherapies.