To study the significance of FasL expression in immune escape of colorectal carcinoma. FasL protein expression and the number of tumor infiltrating lymphocytes (TILs) in 80 specimens of colorectal carcinoma were detected by immunohistochemitry. The mRNA of FasL was measured byin situ hybridization in the consecutive tissue slices of 80 colorectal carcinomas respectively. Using terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL0, apoptotic cells were detected in 80 specimens of colorectal carcinoma. The expression of FasL was detected in all 80 specimens, but it was not even in the same or among different tissues. In the consecutive tissue slices, the location of expression of FasL protein corresponded with that of FasL mRNA. In those with FasL extensive expression, the number of TILs was less than that of FasL weak expression (P<0.05), and the apoptotic index (AI) of TILs was higher and that of tumor cells was lower than that of FasL with weak expression respectively (P<0.01). The AI of TILs was correlated with that of tumor cells (r=−0.631,P<0.01). It was suggested that colorectal carcinoma cells can induce the apoptosis of TILs through the expression of FasL, which can counterattack the immune system. This may be one of the mechanisms of immune evasion in colorectal carcinoma.

The focal hepatic lesion caused by local injection of absolute alcohol in rats was evaluated with ultrasonic contrast agent and pathologic examination. Twenty adult Wistar rats weighing about 200 g were injected with absolute alcohol (0.05–0.1 mL each one) on the exterior left lobe of the liver under the monitoring of ultrasound. Pulse inversion harmonic imaging was used to evaluate the focal lesion after bolus injection of ultrasonic contrast agent (0.05 mL/200 g) through caudal vein. Seven days later, the focal lesion was studied again as before. The exterior left lobe of liver with focal lesion was incised and underwent pathologic examination. The results showed that all of the focal lesions could be defined clearly after bolus injection of the ultrasonic contrast agent under the mode of pulse inversion harmonic imaging. There was good correlation between the size of the focal lesion measured by ultrasound on the 7th day after the “ablation” under the mode of pulse inversion harmonic imaging and that gotten by pathologic examination (P=0.39). The focus size measured by ultrasound right after the ablation was larger than that gotten by pathologic examination (P=0.002). It was concluded that ultrasonic contrast agent plus pulse inversion harmonic imaging could be used to assess the size of the focal hepatic lesion caused by local injection of absolute alcohol in rats.