Nanoparticle accumulation in the lymph node is impaired in aged mice

Abstract Vaccine responses are impaired in aged mice and older people. A key first step in mounting successful responses to vaccines is for antigens to access the draining lymph node from the site of injection. Here we tested the hypothesis that nanoparticle drainage to the lymph node is impaired in older mice after intramuscular injection. We observed fewer 20 nm nanoparticles in the draining lymph node in aged mice after intramuscular injection. However, there was no significant difference in the abundance of larger 1000 nm particles in the lymph nodes of aged mice, which are typically transported to the lymph node by antigen presenting cells. This impaired nanoparticle access was associated with changes in lymph node stromal cells, and a reduction in lymphatic endothelial cells in aged mice. These data suggest that access of smaller antigens to the lymph node may be impaired in ageing and may have implications for the initiation of T and B cell responses after vaccination.