Daily rhythms in immune cells influence their movement in lymph nodes and immune responses

Lymphocyte migration through lymph nodes occurs in a non-continuous, circadian manner.

• Homing of lymphocytes to lymph nodes peaks at night onset, while cell exit occurs during the day.
• Significant oscillations in lymphocyte numbers are observed in both lymph nodes and efferent lymph fluid.
• Rhythmic expression of factors that promote migration in lymphocytes is crucial for this circadian pattern.
• Dendritic cell counts also exhibit peaks in sync with lymphocyte activity.
• Diurnal variations in disease severity following immunization for experimental autoimmune encephalomyelitis (EAE) are noted.
• Disruption of T cell clocks eliminates these circadian patterns, highlighting the importance of timing in immune responses.

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