Credit: © Nature Biotechnology

To reach and stimulate the 'dendritic' cells that are part of the immune system, vaccines are often introduced into the skin. However, dendritic cells capable of producing new antigens are most highly concentrated in the lymph nodes. With this in mind, a team of researchers at the Ecole Polytechnique Federale de Lausanne in Switzerland and the Mount Sinai School of Medicine in the US are exploring a nanoparticle-based vaccine delivery method that directly targets the lymph nodes1.

The team, led by Melody Swartz and Jeffrey Hubbell, took advantage of a basic biophysical process to reach their target: the interstitial fluid that naturally flows into the lymphatic system and toward the lymph nodes. To pass through the lymphatic capillaries, however, it was essential that the nanoparticles — which consisted of a polypropylene sulphide core and a block copolymer — be no more than a few tens of nanometres in size.

The surface chemistry of the nanoparticles was tailored to stimulate the immune response of the dendritic cells — a key part of the vaccination process. Although the potential toxicity effects of the nanparticles still need to be investigated, the preliminary success of the lymph-node targeting vaccine — and the fact that it is low cost and easy to produce — are incentives to keep studying these nanoparticle vaccines.