Table 1.
Properties of representative chemically identified adjuvants
| Category | Adjuvant | Receptor | Adaptor | Cytokine | Reference |
|---|---|---|---|---|---|
| Lipid | MPL | TLR4 | MyD88/TICAM-1 | IL-6/TNFα/IFN-β | TICAM in TLR4 pathway predominantly activated |
| Lipopeptide | TLR2 (+TLR1 or TLR6) | MyD88 | IL-6/TNFα | Similar to BCG-peptidoglycan functionally | |
| Oil, squalane | Undefined | Undefined | Unknown | Facilitating retention of antigens in tissue | |
| Protein | Flagellin | TLR5 | MyD88 | IL-6/TNFα | Affecting the function by soluble TLR5 |
| Cholera toxin B | GM1 receptor | G proteins | Involved | Advantage in Ab production | |
| Versican | TLR2 | MyD88 | IL-6/TNFα | Activation of tumor-associated macrophages in microenvironments for the progression of tumor invasion | |
| Nucleic acid | Virus dsRNA | TLR3, MDA5 | TICAM-1/MAVS | IL-6/TNFα/IFN-α/β/IL-12 | Provoking systemic IFN/cytokinemia via the mitochondrial antiviral signaling pathway, a typical adverse event in viral infections |
| Poly I:C | TLR3, MDA5 | TICAM-1/MAVS | IL-6/TNFα/IFN-α/β/IL-12 | Local secretion of IFN/cytokines via TLR3 and systemic cytokinemia and toxicity via MDA5/MAVAS | |
| CpG DNA | TLR9 | MyD88 | IL-6/TNFα/IFN-α/β/IL-12 | Specific activation of pDC but no direct activation of antigen-presenting DCs in humans | |
| STING ligand | cGAS etc. | STING | IL-6/TNFα/IFN-α/β | Ubiquitously expressed to cause cytokinemia | |
| Mineral | Alum | NLR, PG? | ASC/MyD88 | IL-1/IL-6/TNFα/Cox2 | Activation DNA sensors by DNA secretion secondary to local damage to muscle? |
| Surfactant | Saponin | Undefined | Undefined | Involved | Low toxicity surfactant from plants |
| Surfactant | Undefined | Undefined | BAFF/IL-4/IL-12 | Low toxicity surfactant enhancing AID-mediated class-switch and Ab-production |