The prognosis of glioblastoma (GBM) is still dismal despite current multimodality therapy including commonly used well-tolerated chemotherapeutic agent, the temozolomide (TMZ). Whether or not and how TMZ may affect the host responses of tumor-infiltrating lymphocytes (TILs) remains unclear in GBM.
Objective
We try to simulate the clinical situation of in situ chemo-cytotoxicity and immune responses in GBM microenvironment and try to understand the dynamic change of subpopulation of autologous TILs and also the influence of TILs on GBM pathogenesis during TMZ treatment.
Methods
GBM tumor cells and autologous TILs, grown from surgical specimen were tested for TMZ cytotoxicity in vitro. Employing immunofluoro-cytometry, we examined the combined cytotoxic effects of TMZ and autologous TILs on GBM cells, particularly the invasive and un-differentiation properties, represented respectively by the expression of CD9 surface maker and by intracellular nestin content. Changes of T lymphocyte sub-populations including CD4+, CD8+, and CD4+CCR4+CCR6+ Th17 cells, were determined with TMZ treatment and interaction with autologous GBM tumor cells.
Results
Although both TMZ and autologous TILs did not exert cytotoxicity on GBM tumor cells that contained unmethylated MGMT gene promoters, the autologous TILs seemed to slow down the division time of GBM. The autologous TILs significantly decreased the expression of CD9 cell surface maker and cellular Nestin of GBM tumor cells. TMZ treatment or interaction with autologous GBM did not alter the TIL CD4+, CD8+ subpopulations, but the autologous GBM tumor cells appeared to abrogate an increase in the relative percentage of Th17 component.
Conclusion
TMZ or autologous TILs were not cytotoxic to GBM tumor cells with an active MGMT gene promoter. However, autologous TILs showed greater influences than TMZ on the doubling time of GBM tumor cells, and also on the expression of CD9 and Nestin. Whether this alternation is due to the change of Th17 subpopulation in the microenvironment needs further investigations.
