During early stages of chronic hypoxia under experimental conditions in the lungs alveolar macrophages are activated and in the latter an increased amount of matrix-metalloproteinasecollagenolytic enzymes is produced. Their presence was assessed in the present study in the lungs of infants who died suddenly (SIDS) and also in subjects who died from a violent death incl. acute and protracted external suffocation. The positive findings of these matrixins, in particular MMP-9 (gelatinase) were assessed in alveolar macrophages not only after protracted suffocation but also in the majority of sudden infant deaths. These findings supplement the mosaic of changes which indicate that sudden infant deaths are preceded by a period when the infant was exposed to hypoxia.

        Key words: sudden infant death - chronic hypoxia - metalloproteinases