IMMUNOHISTOCHEMICAL ANALYSIS OF MARKERS FOR DIFFERENT MACROPHAGE PHENOTYPES AND THEIR USE FOR A FORENSIC WOUND AGE ESTIMATION

A total of 117 vital skin wounds (post infliction intervals between a few seconds and 7 months), 20 post mortem wounds and skin specimens wi th beginning or advanced signs of putrefaction were investigated. Diff erent markers for macrophage maturation (27 E 10, RM 3/1, 25 F 9, G 16 /1) were analyzed by immunohistochemistry. The early stage inflammatio n marker 27 E 10 stained macrophages, but also monocytes and neutrophi lic granulocytes localized in blood vessels or bleeding induced postmo rtem and therefore provided no further information for a forensic woun d age estimation in comparison to the routine histological detection o f macrophages. The antigens recognized by the RM 3/1- (intermediate st age inflammation marker) and 25 F 9-antibodies (late stage inflammatio n marker) were expressed exclusively by histiocytes and inflammatory c ells that had migrated from the blood vessels as part of the acute inf lammatory response associated with an intravital reaction. The morphom etrical analysis revealed positive results (defined as at least a two- fold increase in number in 2 or more microscope fields when compared t o the maximum value of histiocytes found in uninjured skin) for the RM 3/1- or 25 F 9-antibody earliest in wounds aged 7 or 11 days, respect ively. Similarly to the 25 F 9-antibody, the chronic stage inflammatio n marker (G 16/1) reacted with a macrophage subpopulation first detect able 12 days after wounding but showed positive results in a comparabl y reduced percentage of cases. On the other hand, this marker did not stain a relevant number of resident macrophages thus facilitating the evaluation of the specimens. The markers 27 E 10, RM 3/1 and 25 F 9 ar e also useful for the evaluation of slightly - even though the stainin g intensity was considerably reduced - but not advanced putrefied skin . Therefore, the immunohistochemical analysis of the corresponding ant igens can possibly contribute to an age estimation of wounds with adva nced post infliction intervals obtained from corpses with longer - but limited - postmortem intervals.