CX3CR1 and toxoplasmosis: However, during toxoplasmosis, endothelial cells of the blood brain barrier are infected [45] and the data that associates CX3CR1 (a chemokine receptor responsible for leukocyte entry into the CNS [86]) with TCR activation in the vascular compartment of the CNS implies that antigen stimulation at the blood brain barrier may induce T cell extravasation into the parenchyma.