[Inhibition of excretory - secretory antigens on growth of murine Lewis lung carcinoma].

OBJECTIVE

To investigate the effect of excretory-secretory antigens (ESA) on CD4 CD25 Foxp3 T (Treg) cells in mice carrying Lewis lung carcinoma, and examine the inhibitory effect of ESA on tumor growth.

METHODS

C57BL/6 mice were randomly assigned into the PBS group ( = 14) and the Lewis group ( = 34). Mice in the Lewis group were subcutaneously injected with 2 × 105 Lewis lung carcinoma cells in the right axilla, while animals in the PBS group were injected with the same volume of sterile PBS. On day 7 post-injection (D7), mice in the PBS group were further divided into the PBS2 group and the PBS2 + ESA group, of 7 mice in each group, and mice in the Lewis group were further divided into the Lewis2 group and the Lewis2 + ESA group, of 17 mice in each group. Then, mice in the PBS2 + ESA group and the Lewis2 + ESA group were intraperitoneally injected with 100 μL of ESA. The mouse spleen coefficient was calculated in each group 7 days post-injection with ESA, and the changes of Treg cell counts and the long-term tumor growth were measured in tumor-bearing mice.

RESULTS

The spleen coefficient was significantly greater in the PBS2 + ESA group and the Lewis2 + ESA group than in the PBS2 (0.66% ± 0.09% vs. 0.30% ± 0.02%, < 0.05) and Lewis2 groups (0.69% ± 0.07% vs. 0.33% ± 0.03%, < 0.05) 7 days post-treatment with ESA, respectively, and the percentage of splenic Treg cells in splenocytes was significantly lower in the PBS2 + ESA group and the Lewis2 + ESA group than in the PBS2 (1.28% ± 0.14% vs. 2.06% ± 0.07%, < 0.05) and Lewis2 groups (1.58% ± 0.14% vs. 2.44% ± 0.23%, < 0.05), respectively. ESA treatment caused a delay in tumor growth, and the tumor size was significantly smaller in the Lewis2 + ESA group than in the Lewis2 group ( < 0.05).

CONCLUSIONS

ESA may reduce the proportion of splenic Treg cells in splenocytes and inhibit tumor growth in mice carrying Lewis lung carcinoma.