ABSTRACT
To estimate postmortem interval [PMI], the spontaneous conversion of the native third component of complement [C3] to its derived fragments in whole blood was studied by immunodiffusion method. Thirty adult albino rats with average weight ranging from 380-400 g were used in this experiment. Immediately after death by decapitation, the collected blood samples were incubated at 37°C, 23°C and 14°C. Sera from each sample were removed every 12 h at 37°C until 60 h, every day at 23°C until the fifth day, and every two days at 14°C until tenth days. The percent age of cleavage of the third component of complement [C3] were assayed. Statistical analysis of the results showed that the incubation of whole blood at a higher temperature led to a faster conversion of beta IC [native C3] to beta IA [C], the cleavage% age at 37°C was about 3 times as that at 14°C [360 mg%. 258 mg% respectively]. Also, there was a significant positive correlation between the percent ages of C3 cleavage and PMI, at the temperatures of [37, 23, 14°C], the correlation coefficients [r] were 01981, m 01.99436, 0.9549 respectively. Therefore, the percent age of C3 cleavage could be used as a marker for estimation of the time passed since death, and this unusual approach could be a step towards the development of an accurate method for determining PMI