Depletion of CD4+CD25+ regulatory T cells can promote local immunity to suppress tumor growth in benzo[a]pyrene-induced forestomach carcinoma

Table 1 Depletion of CD25⁺ regulatory cells suppresses forestomach tumor growth

Group	Body wt. (g)/mouse	Stomach wt. (g)/mouse	% of mice with tumors	Tumors/mouse	Tumor vol. (mm3)/tumor	Total tumor vol. (mm3)/mouse
16 wk
Control	34.7 ± 3.1	0.30 ± 0.02	0 (0/3)	0	0	0
BaP-only	33.5 ± 2.7	0.34 ± 0.02	100 (3/3)	5.3 ± 1.2	2.8 ± 0.5	15.0 ± 5.0
BaP + IgG	35.0 ± 2.9	0.32 ± 0.04	100 (6/6)	6.2 ± 1.3	2.5 ± 0.8	15.2 ± 4.2
BaP + PC61	33.5 ± 2.7	0.30 ± 0.03	100 (3/3)	3.7 ± 1.5a	0.8 ± 0.5b	3.1 ± 2.4b
BaP + PC61/5 wk1	32.3 ± 8.2	0.31 ± 0.05	100 (4/4)	4.3 ± 1.5	1.0 ± 0.5b	4.6 ± 2.8b
24 wk
Control	36.0 ± 3.3	0.33 ± 0.01	0 (0/5)	0	0	0
BaP + IgG	35.6 ± 2.9	0.44 ± 0.08	100 (5/5)	ND	ND	ND
BaP + PC61	36.4 ± 4.1	0.32 ± 0.02b	100 (5/5)	ND	ND	ND
32 wk
Control	36.0 ± 4.5	0.35 ± 0.03	0 (0/3)	0	0	0
BaP-only	36.7 ± 2.1	ND	100 (3/3)	ND	ND	ND
BaP + IgG	36.0 ± 2.5	0.53 ± 0.12	100 (4/4)	15.5 ± 4.2	21.1 ± 16.4	276.8 ± 134.5
BaP + PC61	39.7 ± 8.5	0.44 ± 0.03	100 (4/4)	8.3 ± 2.2a	6.8 ± 3.2	57.1 ± 33.6a

¹Mice were treated with anti-CD25 mAb twice a wk beginning 5 wk after benzo[a]pyrene treatment.

^aP < 0.05,

^bP < 0.01 vs BaP/IgG group; ND: Not determined.

Table 2 Effects of depleted Tregs on tumor formation

	Time	BaP+IgG	BaP+PC61
Infiltrating cells	16 wk	-/+	+
	32 wk	-/+	+++
Apoptotic cells	16 wk	-	+
	32 wk	+	+++
Apoptosis occurred in tumor nodules	16 wk	-	+
	32 wk	-	+++

+++: Severe; ++: Moderate; +: Mild; -/+: Few; -: Not found.