Immunohistochemical characterization of alveolar macrophages and pulmonary giant cells in fatal asphyxia

It is in dispute whether the occurrence of numerous alveolar macrophages and in particular pulmonary giant cells in cases of fatal asphyxia is associated with agonal activation and proliferation. The nature of these alveolar cells was investigated in selected fatalities with protracted final oxygen lack using immunohistochemistry (APAAP method) and a semi-quantitative graduation. The study included opiate-involved deaths (n = 22), fatal strangulations (n = 10) and a control group of sudden cardiovascular deaths (n = 10). Positive immunohistochemical reactions were observed with the monoclonal antibodies PG-M1 (general marker of macrophages, detection of nearly 100% of pulmonary macrophages and giant cells in all subgroups) and 25 F 9 (late stage inflammation marker, detection of pulmonary macrophages/giant cells in 70%/50% of opiate-involved fatalities, 70%/20% of strangulations and 40%/30% of control cases). The antibodies LN-4 (macrophages), 27 E 10 (early stage inflammation marker), AMH 152 (activated macrophages) and MIB 1 (proliferation marker) did not react with these cell populations. Conclusions: pulmonary giant cells and numerous alveolar macrophages are not restricted to asphyxia. Their appearance is not of pathognomonic value for this diagnosis. Both cell types seem to be of heterogeneous nature (different functional state) as only one marker was expressed by all cells. The results do not suggest prefinal immigration, mobilization or proliferation of alveolar cells, but rather point to a longer pre-existence of macrophages and giant cells in pulmonary tissue (25 F 9 as late stage inflammation marker positive).