MAPT and nervous system disorder: Importantly, future studies should also investigate what drives the phenomena of increased T cell clonality and reactivity in neurological diseases: we postulate that altered lymphatic drainage of CNS-derived antigens (Aβ, Tau, α-synuclein or persistent virus) and/or reduced immune cell egress (of T cells or antigen presenting cells) through meningeal lymphatics into the CLNs with aging (Figure 2), might contribute to the above-mentioned changes in CNS adaptive immunity.