CD4 and glioblastoma: However, as no data regarding the intrathecal and intraparenchymal immune response were available for our in-depth glioblastoma cohort, we cannot rule out recruitment of certain immune cell subsets to the CNS, which is (taking into consideration previous data [54–57]) likely to account for the reduction in several CD4+ Tc subsets in the PB of our in-depth RRMS cohort.