Pulmonary surfactant-associated protein A (SP-A) is an exclusively lung specific protein, and is considered to leak into the blood stream in alveolar septal damage. In this study we examined the serum SP-A level in forensic autopsy materials using an enzyme immunoassay with monoclonal antibodies to assess the postmortem level in relation to the cause and mode of death. Although a gradual postmortem degradation should be taken into consideration, topological relationship of serum level seemed to be fairly stable (arterial≥venous blood in most cases), indicating no evident influence of postmortem diffusion. Significant elevation of serum SP-A (76.7-250 ng/ml in left heart blood) was observed in hyaline membrane diseases from various causes independent of the postmortem intervals (<30 h). However, mean SP-A levels in postmortem heart blood were usually low in asphyxia including hanging, strangulation and choking (left, 25.5 ng/ml; right, 22.3 ng/ml), polytrauma (left, 13.1 ng/ml; right, 9.0 ng/ml) and stab wound to the neck (left, 34.1 ng/ml; right, 29.4 ng/ml). Prominent elevation was noted in a case of fatal strangulation with complication of idiopathic interstitial pneumonia, and also in some deaths due to drowning, burns in fires, blunt and gunshot chest injuries. These findings indicated that postmortem elevation of serum SP-A levels was associated with alveolar septal damage due to inflammation, mechanical and physical stresses, which caused leakage of SP-A into the bloodstream. (C) 2000 Elsevier Science Ireland Ltd.
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