An immunohistochemical study on pulmonary surfactant of infants diagnosed as sudden infant death syndrome.

Pulmonary tissues from 22 autopsy cases diagnosed as sudden infant death syndrome (SIDS) were examined by immunoperoxidase method using monoclonal antibodies against human pulmonary surfactant apoproteins. In all cases except one, a moderate or large amount of pulmonary surfactant existed in the alveolar spaces. In the cytoplasm of the alveolar type II cells of most cases, a variable number of reaction products were also recognized. This study suggested that SIDS babies suffered lethal hypoxic state, but the staining intensity of pulmonary surfactant did not show a clear difference in sleeping positions.