Nanoparticles could boost vaccine response

Published: 23-Jan-2012

US researchers create vaccine adjuvant that travels from point of injection to lymph nodes


Researchers at Duke University Medical Centre in the US have created synthetic nanoparticles that target lymph nodes and boost the body’s response to vaccines.

The nanoparticles are described in the journal Nature Materials.

Currently all other adjuvants are thought to enhance immunity at the site on the skin where the vaccine is injected rather than going to the lymph nodes, where the most effective immune reactions occur.

The Duke University study used mice to show that it is possible to shift the delivery path directly to the lymph nodes.

The researchers observed that mast cells, which are found in the skin and fight infections, also communicate directly to the lymph nodes by releasing nanoparticles called granules.

These synthetic granules consist of a carbohydrate backbone that holds tiny, encapsulated inflammatory mediators such as tumour necrosis factor (TNF). When injected, they mimic the attributes of the granules found in natural cells, and also target the draining lymph nodes and provide for the timed release of the encapsulated material.

Traditional vaccine adjuvants may help antigens to persist, providing the body with an immune reaction and build antibodies so that when a real pathogen, such as the flu virus arrives, it will be conquered.

Alternatively, adjuvants may activate dendritic cells, which pick up pathogen parts and must travel from the skin to lymph nodes where immune reactions are initiated.

The Duke team has created a vaccine adjuvant of nanoparticles that are capable of travelling from the point of injection to the lymph nodes, where they act on many cell types of the immune system.

To test this, they vaccinated mice against influenza A virus, adding the nanoparticle granules.

When exposed to a level of the flu virus that would normally prove lethal, the vaccinated mice had an improved survival rate.

The researchers said they could load the same type of particles with a different immune factor, IL-12, that directed a response towards a different set of lymphocytes.

Senior author Dr Soman Abraham, professor of pathology, immunology and molecular genetics and microbiology at Duke in Durham, NC, and emerging infectious diseases at Duke-NUS, is cautiously optimistic that the synthetic particles could make their way into human use soon.

‘It should not be long because all the individual cytokines (immune system factors) and additional materials loaded into these particles are already FDA approved for use in humans,’ he said.

‘There is a lot of interest in nanoparticle-based therapy, but we are basing our materials on our observation of mast cells in nature. This is an informed application to deliver the right material to the right place in the body to get the most effective immune reaction.’

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