Immunohistochemical investigation of pulmonary surfactant-associated protein A in fatal poisoning

To evaluate the immunohistochemical distribution of pulmonary surfactant-associated protein A (SP-A) in fatal poisoning in relation to the effects of drugs and poisons on respiratory function, 42 forensic autopsy cases were examined by scoring the staining intensity. The highest scores of SP-A staining, with dense granular deposits (aggregates) in the intra-alveolar space, were observed in fatalities from pancuronium bromide (muscle relaxant) injection and petroleum (butane) gas inhalation. Poisoning with organophosphate pesticides and arsenic (ingestion) showed a second grade SP-A score. However, The SP-A scores were relatively low in ethanol and sedative-hypnotic intoxication. Carbon monoxide intoxication showed a varied degree of SP-A score, and the aggregated SP-A score tended to be higher in cases of lower blood carboxyhemoglobin concentration. A varied SP-A score was also observed in methamphetamine fatalities, in which the score was relatively low in cases with a higher serum drug level. Increase of SP-A was not always associated with the intra-alveolar effusion or hemorrhages. The above-described observations suggested that the immunohistochemical score of SP-A may be a possible indication for intensity and duration of drug/poison-dependent respiratory distress.