Is lingual tonsil a preferential target for processing sublingually administered materials?

The oral cavity is a site of pivotal importance in the immune response to foreign antigens, ensuring tolerance induction to harmless agents but reactivity to potentially noxious antigens. Tolerance or reactivity are driven by a number of secondary lymphoid organs, all belonging to the Waldeyer ring, that include adenoids, tubal, palatine and lingual tonsils. Waldeyer’s ring tissues were acknowledged as implicated not only in the adaptive immune system but also in the innate immune system modulation, involving the toll-like receptors. In particular, findings from animal studies suggested that the lingual tonsil can be considered as an inductive site sampling and processing antigens to stimulate naïve T and B lymphocytes. According to a recent study showing that immunologically active or inactive materials placed under the tongue of allergic subjects rapidly reach the lingual tonsil, such a role seems likely also in humans, and warrants to be investigated in-depth for possible applications in medical treatments.