CD4 and Parkinson disease: The microglial activation and recruitment (microgliosis) process is accompanied by increased cytokine levels.220 Elevated levels of cytokines (including IL1β, IL2, IL6, IFNγ, and TNFα) and CD4+ lymphocytes have been detected in both serum and CSF of PD patients.221,222 By analyzing snRNA-seq data from postmortem midbrain samples of PD patients and controls, the researchers observed an increased number in reactive microglia and a reduction in oligodendrocyte numbers in PD patients.