Primate Monocytes - CD14, CD16 - Ziegler-Heitbrock

beta2-Adrenergic receptor signaling mediates the preferential mobilization of differentiated subsets of CD8+ T-cells, NK-cells and non-classical monocytes in response to acute exercise in humans.

Abstract

Acute exercise preferentially mobilizes cytotoxic T-cells, NK-cells and non-classical monocytes to the bloodstream under the influence of hemodynamic forces and/or beta2-adrenergic receptor (beta2-AR) signaling. However, the relative contribution of these mechanisms to the redeployment of the most exercise-responsive cell types is largely unknown. We determined the lymphocyte and monocyte subtypes mobilized to blood during exercise via beta2-AR signaling whilst controlling for beta1-AR mediated reductions in hemodynamic forces. In a randomized, double blind, complete cross-over design, 14 healthy cyclists exercised for 30-minutes at +10% of blood lactate threshold after ingesting: (1) a placebo, (2) a beta1-preferential antagonist (10 mg bisoprolol), or (2) a non-preferential beta1 + beta2-antagonist (80 mg nadolol) across three trials separated by >7-days. Bisoprolol was administered to reduce hemodynamic forces (heart rate and blood pressure) during exercise to levels comparable with nadolol but without blocking beta2-ARs. The mobilization of total NK-cells, terminally differentiated (CD57+) NK-cells, central memory, effector memory and CD45RA+ effector memory CD8+ T-cells; non-classical monocytes; and gammadelta T-cells were significantly blunted or abrogated under nadolol compared to both bisoprolol and placebo, indicating that the exercise-induced mobilization of these cell types to the blood is largely influenced by beta2-AR signaling. Nadolol failed to inhibit the mobilization of classical monocytes, CD4+ T-cells (and their subsets) or naive CD8+ T-cells, indicating that these cell types are mobilized with exercise independently of the beta2-AR. We conclude that the preferential mobilization of NK-cells, non-classical monocytes and differentiated subsets of CD8+ T-cells with exercise is largely dependent on catecholamine signaling through the beta2-AR. These findings provide mechanistic insights by which distinct lymphocyte and monocyte subtypes are preferentially mobilized to protect the host from anticipated injury or infection in response to an acute stress response.