Table 4. Numbers of apoptotic cells and BrdU-positive cells in human HCC tumors subcutaneously transplanted in nude mice.

	Apoptosisb (Number of cells/0.25mm2)		BrdU Labeling Indexc (Number of positive cells/0.25mm2)
Treatment groupa	HE stain	TUNEL method
Control	8.4 ± 0.8d,e	9.6 ± 1.1e	32.3 ± 1.6f
PEG-IFN-α2a (0.06 μg)	12.2 ± 1.0	15.4 ± 1.8	27.0 ± 2.6
PEG-IFN-α2a (0.6 μg)	12.4 ± 0.9	16.1 ± 1.5	31.3 ± 6.9

^a Cultured HAK-1B cells (1.0 X 10⁷) were subcutaneously transplanted into nude mice. Five groups of 8 mice received either phosphate-buffered saline (PBS) (Control) or PBS with the different dosages of PEG-IFN-α2a (0.06–60 μg) once a week. Tumors of mice that received 6 or 60 μg of PEG-IFN-α2a could not be used because the tumors were too small to evaluate. All mice were killed on the 15th day. ^b The number of apoptotic cells was counted in at least three 0.25 mm²-areas in each section stained with hematoxylin and eosin, and the average number per area in each group was obtained. The number of TUNEL-positive cells was also counted in the same manner. ^c The number of BrdU-positive cells was counted in at least three 0.25 mm²-areas in each section, and the average number per area in each group was obtained as the labeling index. ^d Mean ± SE. ^e P < 0.02, versus the other groups. ^f. Not significant, versus the other groups.