Table 3.

Various stages of CD4+ T cells infiltration of the BBB.

Stage	Component	Result of Stage Completion
Rolling stage	VCAM1 bind to VLA4 on CD4+ T cells	Weak bonds that reduce the speed of CD4+ T cells
Activation stage	e.g., CCL19 and CCL21 expressed on endothelial cells activate CD4+ T cells	CD4+ T cells are activated
Arrest stage	VCAM1 and ICAM bind to their ligands to mediate T cells arrest	CD4+ T cells attached to the endothelial cells
Diapedesis	V-cadherin gets phosphorylated	the catenin is released
	PECAM upregulation	Activate kinesin molecular motors
	LRBC trafficking	Expand the distance between endothelial cells