Applying the anti-skin cancer drug imiquimod at a vaccine site boosts response
As sadly revealed by the coronavirus pandemic, reduced immunity makes elderly people more vulnerable to infectious diseases, but it also means they respond less strongly to vaccines. Following vaccination, dendritic cells that have encountered a foreign antigen [molecule from the pathogen] travel to our lymph nodes, where they activate antibody-producing B cells to multiply in germinal centres , with assistance from T helper cells. In older lymph nodes, reduced stimulation from dendritic cells after vaccination leads to the formation of fewer of these essential T cells (pictured, in green, in lymph nodes from young (top) and old mice (below)), generating a weaker response overall. Yet researchers found a way to overcome these defects in immune activity, by applying the drug imiquimod at the vaccination site. Currently used in creams to treat genital warts and some skin cancers, imiquimod boosted T cell numbers in older mice, raising the possibility that age-related declines in immunity can be corrected.
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