ABSTRACT
Objective To investigate the differences in susceptibility to Lewis lung carcinoma and T lymphocyte subsets in the immune microenvironment between young and elderly mice.Methods Six C57/B6 mice at two months(young)and six mice at twelve months(aged)were injected with Lewis lung carcinoma cells at the dose of 1 × 106 in the left armpit to establish a murine model of lung carcinoma.The weight and tumor growth were monitored.Blood samples for routine blood tests were collected after 24 days.The proportions of CD4+ and CD8+T cells in the spleen were detected by flow cytometry,and the infiltration of CD4+,CD8+ T cells and related effector T cells in the tumor microenvironment were determined in the same way.Results The body weight of tumor bearing mice in the aged group was significantly higher than that in the young group(P ＜0.001);The tumor weight in the aged group(5.084±0.528)g was significantly higher than that in the young group(2.963 ±0.378)g(t =3,349,P =0.012);Routine blood tests showed that the numbers of leukocytes and subsets(except mononuclear)in the aged group were significantly lower than in the young group(P ＜0.05);Flow cytometry found that the effector and memory/effector CD4+T cell ratios in the spleen were significantly higher in the aged group than in the young group(P ＜0.001)and the expression of effector and memory/effector CD8+T cells in the tumor microenvironment was also significantly higher than in the young group(P ＜0.05);Quantitative expression values of IL-6 and IL-10 in the tumor microenvironment were 25090±3820 and 10670± 1793 in the aged group and 6252±864 and 3061±451 in the young group,respectively.Moreover,the expression levels of IL-6 and IL-10(t =3.925,P =0.01;t =3.552,P =0.02)in the tumor microenvironment in the aged group were significantly lower than those in the young group.Conclusions Young mice are more susceptible to Lewis lung carcinoma,probably as a result of differences in inflammation and immunity.