Collectively, surface expression analysis of CX3CR1 identified a subset of CX3CR1high Teff and CX3CR1int memory (Tem, Tpm) CD8+ T cells in the circulation of grade 4 glioma patients with potentially elevated tissue surveilling properties in the case of Tpm, which are, however, largely absent in the tumor microenvironment. The gene discussed is CX3CR1; the disease is glioma.