Effect of Autolysis onImmunohistochemical Examination of the CNS

Overview

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 ubiquitinein cerebral tissue. The examination was made in 6 deceased subjects without mechanical injury ofthe CNS and 6 subjects with a craniocerebral injury who survived from 6 hours to 3 days. In alldeceased subjects the post-mortem examination was made within 24 hours after death. For immu-nohistochemical examination tissue excisions were taken from standard sites of the brain. Thefirst tissue excisions were immersed into 10% formol after a post-mortem interval of 24 hours. Theremaining tissue slices were subjected to autolysis at room temperature and gradually immersedinto 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 withalkaline phosphatase was selected.In the group of 6 subjects who died after a craniocerebral injury in 4 instances axonal lesionswere detected, i.e. axonal oedema or formation of retraction spheroids.The damaged axons werepositive on examination with all investigated antibodies, whereby it was possible even aftera 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 wasfound, however, it was not positive with anti-NSE antibodies nor with anti-beta-APP .After the24-hour post-mortem interval in this group in 3 instances ubiquitine positivity was found in axonsbut already after a post-mortem interval exceeding 2 days the axons were ubiquitine positive inall 6 subjects. Lumpy deposits of this substance could be detected in axons also beyond axonalstructures.

Key words:
immnohistochemistry - neurone-specific enolase - b-amyloid protein precursor - ubiqu-itine - autolysis