A primary role for human central memory cells in tissue immunosurveillance

Area of Science:

• Immunology
• Cellular Biology
• T cell biology

Background:

• Central memory T cells (T_CM) are traditionally known for patrolling lymph nodes and providing central immunosurveillance.
• Their role in primary tissue immunosurveillance has not been previously established.

Purpose of the Study:

• To investigate the tissue-homing capabilities and functional roles of human central memory T cells (T_CM).
• To determine if T_CM cells participate in primary immunosurveillance of peripheral tissues.

Main Methods:

• Analysis of tissue-homing addressin expression in human T_CM versus effector memory T cells (T_EM).
• Detection of T_CM presence in healthy human tissues (skin, lung, colon, cervix).
• Assessment of effector functions, including cytokine production by CD8+ T_CM.
• In vivo migration and inflammation induction studies using human skin-grafted mice.

Main Results:

• The majority of human T_CM exhibited tropism for skin or gut, with tissue tropism comparable to T_EM.
• T_CM were found in healthy peripheral tissues, indicating a role in primary immunosurveillance.
• A significant proportion of CD8+ T_CM displayed potent effector functions, producing various cytokines.
• In mice, injected human T_CM migrated to skin and induced inflammation similar to T_EM.

Conclusions:

• Human T_CM express peripheral tissue-homing receptors, are present in healthy tissues, and possess strong effector functions.
• These findings support a novel role for T_CM in the primary immunosurveillance of peripheral tissues.
• Long-lived T_CM cells play a crucial role in tissue-based immune responses.