Table 1.

Tissue specific leukocyte rhythmic homing and their effects.

Organ	Rhythmic homing cells	Driving molecules		Conditions	Effects	Reference
		Leukocyte	Vascular bed
Lymph node	CD4 T cells, CD8 T cells	CCR7	CCL21	Steady state /EAE/Helicobacter pylori/influenza A virus	Heightened acquired immune function when stimulus occurred while lymphocytes accumulated in the lymph nodes	(20)
	CD4 T cells, CD8 T cells	CXCR4		Steady state	More rapid proliferation and efficient migration of lymph node T cells at night	(21)
Bone marrow	Neutrophils	CXCR4	CXCL12	Steady state	Neutrophil clearance modulates the hematopoietic niche, which contributes to the rhythmic egress of hematopoietic progenitors	(22)
Lung	Neutrophils			Steady state	Neutrophil aging and apoptosis	(3, 23)
			CXCL5	Inflammation	Time of day variation in the pulmonary inflammation and responses to bacterial infection	(24)
	B cells	CXCR4, CD11a, and CD49d	VCAM-1, ICAM-1	Steady state	Neutrophil aging and apoptosis	(3, 23)
Heart	Neutrophils	CXCR2	VCAM-1, ICAM-1, CXCL1, CXCL2, CXCL5, CCL3, and CCL5	Myocardial infarction	MI at ZT13 induces enhanced neutrophil infiltration and leads to poor prognosis	(25)
	Monocytes	CCR2	CCL2	Myocardial infarction	MI at ZT13 induces enhanced monocytes infiltration	(26)
Vessel	Neutrophils and monocytes	CCR2	CCL2	Atherosclerosis	Timed regime of blocking CCR2 during the activity phase inhibits atherosclerosis	(27)
	Neutrophils	CD11a, CD11b, CCR2 (artery) CD11a, CD11b, CCR2, CXCR2 (vein)	ICAM-1, VCAM-1	TNF-α induced acute inflammation	Time shifted leukocyte recruitment between artery and vein results in different thrombus formation time	(28)