Introduction
T Cell Biology and the Challenge of “Immune Geography”
How Are Tissue Resident T Cells Defined?
Factor | Expression | Function | References |
---|---|---|---|
CD103 | Expressed mainly on CD8+ TRM in certain tissues (e.g., gut) | Interacts with E-cadherin, tethering CD8+ TRM to epithelial cells | |
CD69 | Expressed on most, but not all TRM | Associates with and inhibits S1PR1, blocking tissue egress | |
KLF2 | Downregulated in TRM | Transcription factor required for S1PR1 expression | |
S1PR1 | Downregulated in TRM | Mediates tissue egress in response to its ligand, S1P | |
T-bet | Downregulated in TRM | Transcription factor that suppresses TRM differentiation | |
Eomesodermin | Downregulated in TRM | Transcription factor that suppresses TRM differentiation | |
Hobit | Upregulated in mouse but apparently not human TRM | Suppresses KLF2, central regulator of mouse TRM | |
Blimp-1 | Collaborates with Hobit in mouse TRM | Central regulator of mouse TRM | |
mTOR kinase | Expression may be required for accumulation of mouse TRM | Regulator of cell differentiation and survival | |
FABP4, FABP5 | Required for long-term survival of TRM in mouse skin | Fatty acid binding proteins, promote lipid uptake and transport | [24•] |
Runx3 | Promotes mouse TRM differentiation and maintenance | Transcription factor that regulates tissue-residency in multiple cell types | |
P2RX7 | Supports long-lived TRM | Sensor for extracellular ATP; detects injury and inflammation | [26•] |
Bhlhe40 | Required for development and polyfunctionality of CD8+ TRM and TIL | Transcription factor; programs mitochondrial metabolism and active chromatin state | [27•] |