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The mechanisms underlying the transport of vaccine antigens from the site of administration to the draining lymph node are poorly understood. Until today, it was widely accepted that vaccine antigens were taken up in non-lymphatic tissue by dendritic cells and then transported to the so-called T-cell site of draining lymph nodes where the immune response of the organism was triggered. However, several experiments have now shown that vaccine antigens can reach the lymph nodes via pathways other than the dendritic cells.

Researchers in virology and immunology at INRA in Jouy-en-Josas, associated with another group in Tours, sought to discover more about this phenomenon. They worked on inoculations of a vaccinal strain of salmonella (Salmonella abortuvosis) in the oro-nasal sphere of a sheep, and discovered that these salmonella inoculations induced an accumulation of non-dendritic myeloid cells in the lymph nodes. The salmonella vaccine strain was rendered fluorescent in these cells, and mainly detected associated with granulocytes and monocytes, and to a lesser extent with dendritic cells.

The researchers tried to push this research further in order to understand how the bacterial strain reached the draining lymph nodes. They thus developed a novel lymphatic catheterisation strategy in ewes to enable the real-time monitoring of antigen transport from the oro-pharyngeal sphere. They were able to demonstrate precisely that the vaccine strain could travel alone or associated with granulocytes in the lymph to the T-cell areas of draining lymph nodes, and that introduction of the vaccine strain also induced a major flux of these phagocytic cells in the afferent lymph.

This research opens perspectives for the targeting and use of granulocytes as transporters in the antibacterial vaccine response.

For further information:

• Bonneau, M., Epardaud, M., Payot, F., Niborski, V., Thoulouze, M.I., Bernex F., Charley, B., Riffault, S., Guilloteau LA, Schwartz-Cornil, I. Migratory monocytes and granulocytes are major lymphatic carriers of particulate antigens from oro-nasal mucosae to T cell area of draining lymph node. J. Leuk. Biol. 2006. 79: 268-276

• Schwartz-Cornil, I., Epardaud, M., Albert, J.P., Bourgeois, C., Gérard, F., Raoult, I., Bonneau, M. 2005. Probing Leukocyte Traffic in Lymph from Oro-nasal Mucosae by Cervical Catheterization in a Sheep Model. Journal of Immunological Methods. 305 : 152-161.