How adrenaline-related signals regulate immune response by daily movement of immune cells through lymph nodes

Lymphocyte egress from lymph nodes is reduced at night due to inputs from adrenergic nerves.

• Diurnal variations in lymphocyte recirculation through lymph nodes are linked to the time of day.
• Neural inputs to β-adrenergic receptors on lymphocytes affect their movement, with fewer lymphocytes leaving lymph nodes at night.
• Increased lymphocyte accumulation in lymph nodes at night correlates with enhanced antibody responses following immunization.
• The dependence of humoral immune response on β-adrenergic signaling suggests a novel mechanism for immune system rhythms.
• Stopping lymphocyte recirculation through lymph nodes diminishes the observed diurnal variation in immune responses.

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