Table 2

Proposed mechanisms of adjuvant activity of major adjuvant components



Adjuvant activity

Mechanism of adjuvant action


Aluminum salts

AlOH or AlPO4 non-crystalline gels

Antibody and TH2 cells

↑ Chemokine/cytokine production; ↑ recruitment of monocytes and differentiation to DC; ↑ antigen uptake by DC



Oil (squalene)-in-water emulsion

↑ Ab titre; ↑ Ab cross-reactivity; drives TH2 cells

↑ Chemokine/cytokine production; recruitment of myeloid DCs to injection site; ↑ antigen uptake by DCs


TLR ligands

MPL, GpG, imiquimod, resiquimod (both imidazoquinolinamines) or poly(I:C)

Drives TH1 and CTL cells; ↑ T cell memory

TLR signaling in DCs promotes antigen presentation on MHC I and MHC II, enhanced migration of DCs to lymph nodes and DCs cytokine production; may have direct impacts on lymphocytes



Purified fraction of Quil A that has lower toxicity and retains adjuvant effects

Antibody, TH1 and CTL responses

Enhances protective responses through poorly understood mechanisms; has lytic capacity and local reactogenicity


Abbreviations: Ab, antibody; CTL, cytotoxic T lymphocyte; MPL, monophosphoryl lipid A; poly(I:C), a synthetic analog of double-stranded RNA; Th, T helper cell; TLR, Toll-like receptor.

McKee et al. BMC Biology 2010 8:37   doi:10.1186/1741-7007-8-37

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