Home > Community > What is the mechanism of action of adjuvant QuilA?
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+ T lymphocytes
+ Saponins
+ Dendritic cells
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Moises Chame

What is the mechanism of action of adjuvant QuilA?

Christopher Imoe  Follow

Hi Jean-Jacques, you mention that QuilA is washed off in a dialysis step while making ISCOMs. Is it possible to incorporate QuilA into the vesicle without altering it too much?

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Benjamin Lasseigne  Follow

QuilA is indeed associated with the production of liposomes and iscoms, because it is involved in the stabilization of the lipid bilayer. But this is largely removed by dialysis during particle synthesis process.
It certainly remains saponin, as this confers on the final product very high toxicity when used in an active dose.
On the other hand, it is quite possible that the saponin acts by destabilizing the plasma membranes of cells encountered at the injection site, or by activating certain surface receptors, such as scavengers, DCIR, FAS ...to induce apoptosis in the affected cells or tissue necrosis at the injection site. In both cases the TLR molecules would be solicited, but indirectly.
No direct link has been confirmed for now.

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Andi Quercia  Follow

Saravanan if it is known to promote Th1 and Th2 responses then is it some sort of a TLR agonist? Or does it just promote dendritic cell functions thereby promoting T cell activation?

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Daryl Storey  Follow

QuilA (usually after Quillaja Bark) is a saponin, which has a double action: chelating agent for fatty acids such as cholesterol, and detergent, giving it a wetting power. These combined actions saponin give a particularly effective ability to penetrate cells, which is used by FACS to permeabilize the plasma membrane.
It is possible that the saponin may have an adjuvant effect by altering the injection site, and then by recruiting specialized dendritic cells. But the most likely effect concerns its action on the lipid structure of the antigen injected; may be micelles structures but also changes in the structures of related proteins: formation of new epitopes

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Magnus Alsered  Follow

You can follow the links below to obtain certain valuable and interesting informations:-
1. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2587213/
2. http://www.invivogen.com/review-vaccine-adjuvants

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Chemistry  Follow

Quil A is a partially purified saponin. When it is added to the antigen, it forms a mixed protein saponin micelles. This helps in antigen uptake by the antigen presenting cells and results in both Th1 as well as Th2 responses. It is known to induce moderate CTL response. 

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Austin Mccormack  Follow

Thank you this was very useful

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David Adam Suddit  Follow

Saponin is a detergent and is highly irritant. It does cause cell lysis at the site of injection so incites inflammation that leads to a high but short spike in immune responses to other antigens (yours) in the mix. The rest is up to the local draining lymph node, DCs and the rest. It causes fast release of gIFN in lymph from the local node, probably from NK cells when injected without adjuvant

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Cross-dressing  Follow

Quil A is a partially purified saponin. When it is added to the antigen, it forms a mixed protein saponin micelles. This helps in antigen uptake by the antigen presenting cells and results in both Th1 as well as Th2 responses. It is known to induce moderate CTL response. 

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Angel Wallace  Follow

Jean-Jacques I read about QuilA being further purified to make ISCOMs.  Which are lipid structures with saponin and antigen. Administered orally or through mucosal routes to assess mucosal immune response to a specific antigen (eg., flu).  
Does QuilA  play a role in recruiting dendritic cells or does it also help in their activation? If so, then through which mechanisms?(eg., TLR agonists) 

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