Table 1.
Proposed Homeostatic Roles of Mouse CD1 and Other Nonpolymorphic MHC-like Molecules
| MHC or MHC-like molecule | Functional binding groove | Cargo | Recognition by lymphocyte receptor | Interacting ligand and/or cell types | Proposed homeostatic function |
|---|---|---|---|---|---|
| Classical | |||||
| Class I | + | Peptide | + | CD8/TCR-α/β T cells | Host defense |
| Class II | + | Peptide | + | CD4/TCR-α/β T cells | Host defense |
| Nonpolymorphic | |||||
| CD1 | + | Lipid | + | CD4+ or DN NK, CD8α/α+, γ/δ T cells | Lipid membrane integrity? |
| H2-M3 | + | Formylated peptide | + | CD4/TCR-α/β T cells | Mitochondrial integrity? |
| HLA-E (Qa-1) | + | MHC I leader peptide | + | CD94/NKG2A, B, C NK cells, and CD8+ T cells | Class I MHC expression |
| HLA-G | + | Peptide | + | ILT-2, p49 KIR NK and T cells | Materno-fetal tolerance |
| MIC-A/MIC-B | − | Unknown | + | CD94/NKG2D NK, γ/δ T cells, CD8+ T cells | Gut epithelial integrity? |
| FcRn | − | IgG | + | IgG | Serum Ig |
| ZAG | Probable | Lipid | Unknown | Unknown | Lipid metabolism? |
| HFE | − | TfR | + | Transferrin/iron/TfR | Iron |