Both Th1 and Th2 cells are involved in the pathophysiology of TH and RT conditions. Indeed, human tonsils persistently harbor microbial antigens even when the subject is asymptomatic of ongoing infection. It could also be an effect of ontogeny of the immune system. Clinical significance The pathogenesis of infectious/inflammatory disease in the tonsils most likely has its basis in their anatomic location and their inherent function as organ of immunity, processing infectious material, and other antigens and then becoming, paradoxically, a focus of infection/inflammation. No single theory of pathogenesis has yet been accepted, however. Viral infection with secondary bacterial invasion may be one mechanism of the initiation of chronic disease, but the effects of the environment, host factors, the widespread use of antibiotics, ecological considerations, and diet all may play a role. A recent cross-sectional study revealed a high rate of prevalent virus infections in non-acutely ill patients undergoing routine tonsillectomy. However, none of the 27 detected viruses showed positive association to the tonsillar disease. In children, the tonsils are common sites of infections that may give rise to acute or chronic tonsillitis. However, it is still an open question whether tonsillar hypertrophy is also caused by a persistent infection. Tonsillectomy is one of the most common major operations performed on children. The indications for the operation have been complicated by the controversy over the benefits of removing a chronically infected tissue and the possible harm caused by eliminating an important immune inductive tissue. The information that is necessary to make a rational decision to resolve this controversy can be obtained by understanding the immunological potential of the normal palatine tonsils and comparing these functions with the changes that occur in the chronically diseased counterparts. Acute tonsillitis Tonsillitis is the inflammation of tonsils. Acute tonsillitis is the most common manifestation of tonsillar disease. It is associated with sore throat, fever and difficulty swallowing. The tonsils may appear normal sized or enlarged but are usually erythematous. Often, but not always, exudates can be seen. Not all these signs and symptoms are present in every patient. Recurrent tonsillitis Recurrent infection has been variably defined as from four to seven episodes of acute tonsillitis in one year, five episodes for two consecutive years or three episodes per year for 3 consecutive years. Tonsillar hypertrophy Tonsillar hypertrophy is the enlargement of the tonsils, but without the history of inflammation. Obstructive tonsillar hypertrophy is currently