Abstract
Tumor microenvironment is pretty complex and it might be changed during tumor progression or following therapy. To examine the effect of stroma cells on the behaviors of tumor growth, the relative relationship among tumor cells, brain resident cells, such as microglia, and infiltrating cells, such as monocytic (CD45+CD11b+) or lymphocytic (CD45+CD11b-) lineage cells, was analyzed by flow cytometry. Not only tumor area, peripheral organs, including spleen, blood, and lymph nodes were also examined. The preliminary data showed that microglia had different pattern in ventricles and in the tumor. Furthermore, we found that the change of two subtypes of myeloid derived suppressor cells (MDSCs), Ly6G+ neutrophilic MDSC (N-MDSC) and Ly6G- monocytic MDSC (M-MDSC), was in opposite direction during tumor progression. The increase of M-MDSCs is associated with the increase of tumor size while the N-MDSC is decreased. More interestingly, the population of MDSC is closely related to the change of T cells, in particular after radiotherapy. We also established a brain tumor reporter cell line, ALTS1C1-Luc. We used this cell line to prove that CD8+ T cell had cytotoxicity to tumor cells and this efficiency would be influenced by bearing tumor and radiotherapy. The effect of bearing tumor and radiotherapy on T cell proliferation was also studied. Results show that bearing tumor and radiotherapy have distinctive effect on the cytotoxicity of CD8+ and the proliferation potential of CD4+ T cells.