Effect of autolysis on histochemical examinations of the central nervous system

: The objective of the study was to explain the effect of autolysis on immunohistochemical detection of neurone-specific enolase (NSE), beta-amyloid protein precursor (beta-APP) and ubiquitine in cerebral tissue. The examination was made in 6 deceased subjects without mechanical injury of the CNS and 6 subjects with a craniocerebral injury who survived from 6 hours to 3 days. In all deceased subjects the post-mortem examination was made within 24 hours after death. For immunohistochemical examination tissue excisions were taken from standard sites of the brain. The first tissue excisions were immersed into 10% formol after a post-mortem interval of 24 hours. The remaining tissue slices were subjected to autolysis at room temperature and gradually immersed into formol after 24-hour intervals, the longest post-mortem interval being 168 hours, i.e. 7 days. For visualization of the linked primary antibody the biotin-streptavidin system labelled with alkaline phosphatase was selected. In the group of 6 subjects who died after a craniocerebral injury in 4 instances axonal lesions were detected, i.e. axonal oedema or formation of retraction spheroids. The damaged axons were positive on examination with all investigated antibodies, whereby it was possible even after a 168-hour post-mortem interval to differentiate damaged and not damaged axons. In the group of 6 subjects without mechanical injury of the CNS in 5 instances axonal oedema was found, however, it was not positive with anti-NSE antibodies nor with anti-beta-APP. After the 24-hour post-mortem interval in this group in 3 instances ubiquitine positivity was found in axons but already after a post-mortem interval exceeding 2 days the axons were ubiquitine positive in all 6 subjects. Lumpy deposits of this substance could be detected in axons also beyond axonal structures.