CD4 and central nervous system cancer: In addition to baseline (preoperative/pretreatment) lymphopenia and shifts in the CD4+/CD8+ T cell ratio, it has been repeatedly documented that patients with glioma have decreased serum levels of Th1-type cytokines (IL-2, IL-6, IL-12, TNF-α, and IFN-γ) and increased serum levels of Th2-type cytokines (IL-4 and IL-10) (46, 60–64).