Moving towards a new era in the research of tonsils and mucosal barriers.

The palatine and nasopharyngeal tonsils (adenoids) are lymphoepithelial tissues located in strategic anatomical areas of the oral pharynx and nasopharynx. These immunocompetent tissues represent the first line of defense against ingested or inhaled foreign proteins such as bacteria, viruses, or food antigens. Accompanying the advances being made in the field of medicine today, the role of the tonsils in immunocompetence is becoming extremely important. Upper respiratory tract infections such as acute otitis media, acute rhinosinusitis and acute pharyngo-tonsillitis are diseases that occur with extremely high frequency, and the antimicrobial agents used to treat these diseases account for a large proportion of health care costs. The increasingly refractory nature of upper respiratory tract infections caused by drug-resistant bacteria has become a major worldwide concern. The elucidation of the immune functions of the tonsils and mucosal membranes of the upper respiratory tract is considered to have important significance. The tonsils are also considered to play an important role as one of the causes of sleep apnea syndrome, and have been reported to be intimately involved in the manifestation of IgA nephropathy and palmoplantar pustulosis, a kind of skin disorder. Interest has continued to grow in this symposium with each session ever since it was first held in Kyoto, Japan in 1987. Since then, the symposium has been held every 3-4 years; in Pavia in 1991, in Sapporo in 1995, in Ghent in 1999, in Wakayama in 2003, and in Siena in 2006. Since the 5th symposium in Wakayama, the topics were extended to mucosal barriers of upper airways including the mucosal immune system, innate immunity, and mucosal vaccine. Recent fine technologies and information on molecular biological approaches for upper airways will continue to advance our understanding of epidemiology, etiology, pathogenesis, diagnosis and management of tonsil-related disorders and various upper respiratory tract infections such as otitis media and rhinosinusitis. Moreover, in the era of drug-resistant microbes, we should exert more effort to develop powerful and effective mucosal vaccines against pathogens in upper airways.