Table 2.
Complete list of receptors known to be expressed by intestinal intraepithelial T lymphocytes, their ligands and their context-dependent functions.
| Receptor | Alternative names | Ligands | Ligand expression on IEC | Function | Context |
|---|---|---|---|---|---|
| NKG2D | Klrk1 (gene) | MICA/MICB, ULBP (human) Rae-1, H60, MULT1 (mouse) | Induced56 Induced56 | Costimulatory/stimulatory |
In vitro killing assay55,57,61 Poly(I:C) treatment58 |
| CD160 | By55 |
HVEM (high affinity) Classical and non-classical MHC-I molecules (low affinity) |
Yes74 Yes |
Costimulatory N/A |
Listeria monocytogenes infection75 C.rodentium infection74 |
| CD100 | Sema4D |
Plexins B1 and B2 CD72 |
Yes76 No76 |
Costimulatory | DSS-induced colitis (γδ T-IEL)77 |
| CD8αα | Thymus leukemia antigen (TL) | Yes84 | Inhibitory |
Spontaneous model of T-cell-dependent colitis89 |
|
| Ly49 Family | MHC-I molecules | Yes |
Inhibitory No effect |
In vitro costimulation95 DSS-TNBS-induced colitis and TNFΔARE ileitis model99 AOM-DSS-induced colorectal cancer98 |
|
| CD200R | OX2R |
CD200 iSEC1, iSEC2 |
No102 Yes102 |
Inhibitory | In vitro anti-CD3 stimulation102 |
| CD94 |
HLA-E (human) Qa-1b (mouse) |
Yes124 Yes16 |
Inhibitory (NKG2A dimerization) Costimulatory (NKG2C or E/H dimerization) |
In vitro anti-CD3 stimulation95,105 in vitro anti-CD3 stimulation105 |
|
| 2B4 |
SLAMF4 CD244.2 |
CD48 (SLAMF2) | N/A | Inhibitory | Ex vivo and in vivo anti-CD3 stimulation95 |
| JAML | AMICA1 | CAR | Yes117,118 | Costimulatory | In vitro costimulation (γδ T-IEL only)117 |
| OX40 |
CD134 TNFRSF4 |
OX40L (gp34, CD252, TNFSF4) | No | Costimulatory | In vitro anti-CD3 and anti-OX-40 stimulation119 |
| NKp46 |
CD335 NCR1 |
Various viral and bacterial proteins | Stimulatory | In vitro cytotoxic assay108,120 | |
| NKp44 |
CD336 NCR2 |
Various viral and bacterial proteins | N/A | N/A | |
| LAG-3 | CD223 |
MHC-II molecules FGL1 |
N/A |
N/A | N/A |
| NKR-P1a |
CD161 KLRB1 |
LLT1/CLEC2D (h) | Yes127 | N/A | N/A |
| 4-1BB |
CD137 TNFRSF9 |
4-1BBL (CD137L, TNFSF9) | N/A | N/A | N/A |
| Gp49 |
LILRB4 ILT3 CD85k |
Unknown | N/A | N/A | N/A |
| TIGIT | VSig9, Vstm3, WUCAM |
CD155 CD112 |
Yes128 N/A |
N/A | N/A |
| PD-1 | CD279 | PD-L1 | Induced129 | N/A | N/A |
| CTLA-4 | CD152 | B7.1/2 | Yes130 | N/A | N/A |
N/A no data available, IEC intestinal epithelial cells, T-IEL intraepithelial T lymphocytes, DSS dextran sodium sulfate, TNBS trinitrobenzenesulfonic-acid, AOM azoxymethane.