Comparative evaluation of pulmonary lactoferrin and lysozyme immunoreactivity for the postmortem diagnosis of death due to sepsis.

To determine whether lactoferrin (LF) and lysozyme (LZ) can be used as immunohistochemical postmortem markers of sepsis, pulmonary tissue sections from autopsy cases of sepsis-related fatalities (n = 13) and control cases of non-septic fatalities (n = 14) were evaluated for differences in leucocytic immunoreactivity. LF and LZ were investigated in paraffin sections using the AEC technique. The immunohistochemical expression of both markers was scored, evaluating the quantity of immunopositive cells and the intensity of the intracellular immunoreactivity. There was a statistically significant association between an enhanced expression of LF on pulmonary leucocytes in sepsis-related fatalities in contrast to non-sepsis cases (P < 0.001), whereas no such difference could be observed for LZ immunoreactivity between the two study groups. Pneumonic tissue alterations had no significant influence on LF and LZ immunoreactivity, thus suggesting differences between the degranulation of these non-specific antibacterial agents in local and systemic inflammatory processes. While the variability of LZ immunoreactivity, possibly reflecting a non-specific release from lysosomes according to the length of the postmortem interval, limits its application to the postmortem diagnosis of sepsis, the immunohistochemical detection of an enhanced expression of LF can contribute to the postmortem discrimination between sepsis and non-septic fatalities.