Figure 3.

Neuroimmune cross-talk. Meningeal lymphatics and blood vessels (in the brain parenchyma covered by BBB) drain macromolecules and immune cells (T cells, B cells, ILC2, APC, etc.) to CSF present in subarachnoid space. Immune compounds can further travel to lymph nodes of head & neck where they encounter the rest of the immune system. Peripheral immune cells and cells in brain parenchyma can communicate via cytokines, chemokines, tropic factors and neurotransmitters. T cells via norepinephrine—choline acetyltransferase T cell-acetylcholine axis can suppress immune response. Neurons can communicate a danger by release of alarmins (e.g., IL-33).