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Introduction: CD8 + T-cells and MHC-I have been detected in brain gliomas with a significant outcome. The effect of chemotherapies on the crosstalk interaction between CD8 + T-cells and MHC-I has never been explored., Material and Methods: The protein expression profiling of CD8 cytotoxic T-cells and the gene expression assay of MHC-I in 35 patients diagnosed with WHO grade 4 astrocytoma were performed. The impact of these two factors on tumor recurrence was analyzed., Results: IDH was wildtype in 13 tumors. MHC-I protein expression was absent or low in 34 tumors and dense in a single case. MHC-I gene expression was upregulated in 10 tumors and 25 tumors showed MHC-I gene downregulation. Temozolomide (TMZ) was given to 24 patients and 11 patients received TMZ plus other chemotherapies. No statistically significant association was observed between IDH mutation and CD8 + T-cells ( p = 0.383). However, this association was significant in recurrence-free interval (RFI) ( p = 0.012). IDH-wildtype tumors with highly infiltrated CD8 + T-cells or IDH-mutant tumors with low CD8 + T-cells showed late tumor recurrence. There was a statistically significant difference in RFI between tumors with different MHC-I expression and CD8 + T-cell counts after treatment with TMZ or TMZ plus ( p = 0.026)., Conclusions: No association between IDH mutation and CD8+ cytotoxic T-cell was found. IDH is directly linked to tumor recurrence regardless of CD8 + T-cells infiltration. TMZ plus other adjuvants is proved to be more effective in improving patient survival and delaying tumor recurrence, as compared to using TMZ alone. Nonetheless, none-TMZ adjuvants may increase tumor sensitization to cytotoxic T-cells more than TMZ.

Aim of the Study: Oligodendrocyte transcriptional factor-2 (Olig2) is an essential marker for oligodendrocytes expression. We aimed to explore the expression of Olig2 in different glial neoplasms and to investigate if diffuse Olig2 expression can replace 1p19q co-deletion for the diagnosis of oligodendroglioma., Material and Methods: Olig2 was performed on 53 samples of different glial neoplasms using immunohistochemistry (IHC). 1p/19q deletions were investigated using fluorescence in situ hybridization (FISH)., Results: Olig2 labelling of different glial neoplasms revealed various expressions, in which 26 tumours showed diffuse expression (≥ 60%) and 23 tumours showed partial focal expression (< 50%). Four tumours showed no expression. Of the 26 tumours, 6 oligodendrogliomas had 1p19q co-deletion and the remaining 3 oligodendrogliomas showed no co-deletion. Three non-oligodendroglial tumours were found to have 19q deletion. The FISH of the remaining tumours (14/26) showed no aberrations. There was no significant difference in the final diagnosis by using 1p19q co-deletion test among glial neoplasms with diffuse Olig2 expression (p = 0.248)., Conclusions: Olig2 marker cannot be used as an alternative diagnostic method for 1p19q co-deletion to distinguish oligodendrogliomas from other glial neoplasms. Although some glial tumours showed diffuse Olig2 expression, 1p19q co-deletion testing is the best diagnostic method.