Analysis of the etiology of idiopathic tonsillar hypertrophy (ITH). The major hypothesis is that stimulation of normal tonsils by antigens from bacterial metacolonies causes ITH. This hypothesis is being tested by answering three basic questions: (i) Are metacolonies significantly associated with ITH? (ii) Are there metacolony-common bacterial species across metacolonies? (iii) Do tonsillar B cells from ITH patients recognize antigens from MC-species?