[Hypersensitivity pneumonitis in children. A study of 5 cases (author's transl)].

Five cases of hypersensitivity pneumonitis in children are reported. Four had the pattern of bird breeder's disease and one of aspergillus lung hypersensitivity. All were clearly defined by clinical, radiological, functional and immunologic features. The possible difficulties in diagnosis are emphasized. The disease might be frequently overlooked and its frequency underestimated in children. The diagnostic value of precipitating antibodies is discussed. Although some immunologic studies suggest immune complex mechanisms, recent experimental and clinical data are in favor of a role for cell-mediated immunity. In addition whether or not immunological damage is to occur and result into disease depends not merely upon the characteristics of the antigen exposure. Genetic and/or acquired individual differences in immune reactivity can play a definite role as well. The risk of secondary pulmonary fibrosis and chronic respiratory failure in untreated patients is emphasized. Immunologic and functional tests for identification of the provoking antigen and ceasing of contamination exposure are urgent : they are also useful for monitoring steroid therapy.