In children with recurrent tonsillitis there may be persistent antigen deposition in tonsil tissue. even between exacerbations. If so, upregulation of immunocompetent cells should occur continuously, in contrast to tonsil tissue from children with tonsillar hypertrophy. The cytokine pattern was studied in cell suspensions prepared from tonsils obtained from 12 children undergoing tonsillectomy. The study group comprised 6 children with recurrent tonsillitis and 6 who had a history of tonsillar hypertrophy causing sleep apnea. Cytokine-producing cells (IL-1alpha, IL-1beta, TNFalpha, IL-6, IL-8, IL-2, IFNgamma, TNFbeta, IL-10 and IL-4) were characterized at the single-cell level by use of cytokine-specific monoclonal antibodies and indirect immunofluorescence technique. A constitutive production of IL-1alpha, IL-1beta, TNFalpha, and IL-8 was found in both groups (10-300/10(5) cells). However, the frequency of spontaneous IL-2, IFNgamma, TNFalpha, IL-6 and IL-10 was consistently low (10 +/- 10 cells) in both groups. Following restimulation by T-cell receptor ligation, using immobilized anti-CD3 mAb, with concentrations chosen so that it did not activate resting cells, increased frequencies of TNFalpha, IL-6, IL-8, IL-2, IFNgamma, IL-4 and 1L-10 synthesizing cells were induced in the recurrent tonsillitis group. Significantly higher incidences of IL-1beta, IL-6 and IL-2 producing cells were found in the recurrent tonsillitis group (60-200/10(5) cells, p <0.05). Microbiological evaluation in the tonsil tissue could not reveal tiny differences between the studied groups regarding bacterial or viral pathogens. However, this does not exclude persistent increased intracellular deposition of microbial antigens as a possible explanation for the elevated incidence of IL-1beta, TNF-alpha, IL-6, IL-8, IL-2, IFNgamma, IL-10 and IL-4 expressing cells noticed in patients with recurrent tonsillitis.