“…However, induction of mucosal immunity can take place also in nasopharynxassociated lymphoid tissue (NALT), including the unpaired nasopharyngeal tonsil (adenoids) and the paired palatine tonsils (see Chapter 103), as well as other lymphoepithelial structures of Waldeyer's pharyngeal ring (Brandtzaeg, 1987(Brandtzaeg, , 2011aBrandtzaeg and Johansen, 2005). BALT may also contribute, but this type of MALT is normally absent or rare in healthy lungs of adults although often present in children and adolescents-regularly being detected shortly after birth (Hiller et al, 1998;Heier et al, 2008Heier et al, , 2011.…”