Markers of mechanical asphyxia: immunohistochemical study on autoptic lung tissues

Forensic pathologists are often asked to provide evidence of asphyxia death in the trial and a histological marker of asphyxiation would be of great help. Data from the literature indicate that the reaction of lung tissue cells to asphyxia may be of more interest for forensic purposes than migrating cells. The lungs of 62 medico-legal autopsy cases, 34 acute mechanical asphyxia (AMA), and 28 control cases (CC), were immunostained with anti-P-selectin, anti-E-selectin, anti-SP-A, and anti-HIF1-α antibodies, in order to verify if some of them may be used as markers of asphyxia death. Results show that P- and E-selectins expression in lung vessels, being activated by several types of trigger stimuli not specific to hypoxia, cannot be used as indicator of asphyxia. Intra-alveolar granular deposits of SP-A seem to be related to an intense hypoxic stimulus, and when massively present, they can suggest, together with other elements, a severe hypoxia as the mechanism of death. HIF1-α was expressed in small-, medium-, and large-caliber lung vessels of the vast majority of mechanical asphyxia deaths and CO intoxications, with the number and intensity of positive-stained vessels increasing with the duration of the hypoxia. Although further confirmation studies are required, these preliminary data indicate an interesting potential utility of HIF1-α as a screening test for asphyxia deaths.