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Researchers from Turku, Finland, observed that lymphatic endothelial cells and other stromal cells are the first cells in the lymph nodes to come into contact with vaccines.  (Source: University of Turku)
In-Depth Study

Vaccines Activate Rapid Lymph Node Responses

Vaccines activate a notably rapid response in the stromal cells of draining lymph nodes within the first hours after administration. Researchers have also revealed that the stromal alterations prime the lymph node landscape for the subsequent steps of vaccine-induced immune responses.

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