Supravital expression of heat-shock proteins

•In the investigation of fire deaths, it is important to be able to distinguish vitality at the time of the outbreak and the onset of heat stress.•HSPs are very important proteins for the survival of the organism, with enormous importance in protein homeostasis.•HSP expression can occur in the early supravital period.•The phenomenon of supravital HSP expression must be considered when determining vitality in fire deaths to avoid false conclusions. Heat-shock proteins (HSPs) are expressed during cellular stress, especially thermal stress, to support protein homeostasis. Extensive investigations have revealed that HSP27 is rapidly and intensively expressed in the pulmonary and renal tissues of most cases of death due to fire, contrary to cases without premortem thermal influences, which are negative for HSP expression. As such, HSP27 can be used as a marker of vitality in the investigation of fire-related deaths. Without positive HSP27 expression or only slight expression, one can conclude that the deceased was not alive at the time of heat stress. This is presented in two case reports of men who were shot and later burned. HSP espression could not be found in these cases. In the very early supravital period, particularly the latency and supravital periods, metabolic processes can continue after irreversible cardiac arrest. Extensive cellular stress can lead to an immunohistochemically detectable expression of HSP in this portmortem period. This is shown in the case report of a 49-year-old man who immediately died and burned following the massive detonation of an air mine. Immunohistochemical studies of recovered renal tissues have revealed HSP27 expression in the vessel walls as well as renal tubules, as presented in a third case report. This HSP expression can be considered as a phenomenon of supravitality. Heat stress induces massive cellular stress and the expression of HSP under global ischemic conditions. When vitality is to be determined in cases of suspected fire deaths, the possibility of supravital expression has to be considered.