Md. Piercecchi-marti et al., Immunostaining by complement C9: A tool for early diagnosis of myocardial infarction and application in forensic medicine, J FOREN SCI, 46(2), 2001, pp. 328-334
Before the first 12 hours, diagnosis of early myocardial infarctions is alw
ays difficult for forensic pathologists. We tested complement C9 expression
in 121 formalin-fixed and paraffin-embedded heart samples by an immunohist
ochemical procedure. The heart specimens were separated into four groups: 3
3 cases in group 1 with typical ischemic damages histologically located, 20
cases in group 2 with death related to myocardial infarction on the basis
of ischemic presentation on electrocardiogram but no obvious histological i
schemic damage, 35 cases in group 3 with severe coronary disease without ca
use of death found at the autopsy. and 33 cases in group 3 without sign of
myocardial infarction and without coronary disease. In the first group, all
33 heart samples showed a well-defined C9 expression in the necrotic areas
. The second group in 17 of 20 cases showed positive areas for C9 expressio
n. In the other three heart specimens, only few stained cells were observed
whereas the painful symptoms had begun less than 1 h before death. The thi
rd group showed C9 immunopositive areas in six of 35 cases, few stained cel
ls in 8 cases, and no C9 deposition in the 21 other cases. The last group s
howed no staining area. To avoid nonspecific C9 staining due to tissue auto
lysis, we studied C9 expression during a controlled putrefactive process in
four cases included in group 1; staining was found only in infarcted myoca
rdial areas, and was observed up to ten days. Specificity of C9 expression
was evaluated to be 100% [89.4 to 100%] and sensitivity to be 85% [62.11 to
96.79%]. In conclusion, evaluation of immunohistochemical expression of C9
appears to be a highly sensitive and specific marker of early myocardial i
nfarction, useful in forensic medicine if survival is more than 1 h after t
he beginning of myocyte damage.