Exercise and leukocyte interchange among central circulation, lung, spleen, and muscle

Abstract

Circulating leukocytes increase rapidly with exercise then quickly decrease when the exercise ends. We tested whether exercise acutely led to bidirectional interchange of leukocytes between the circulation and the lung, spleen, and active skeletal muscle. To accomplish this it was necessary to label a large number of immune cells (granulocytes, monocytes, and lymphocytes) in a way that resulted in minimal perturbation of cell function. Rats were injected intravenously with a single bolus of carboxyfluorescein diacetate succinamidyl ester (CFSE) dye which is rapidly and irreversibly taken up by circulating cells. The time course of the disappearance of labeled cells and their reappearance in the circulation following exercise was determined via flow cytometry. The majority of circulating leukocytes were labeled at 4 h. post-injection and this proportion slowly declined out to 120 h. At both 24 and 120 h, running resulted in an increase in the proportion of labeled leukocytes in the circulation. Analysis of the skeletal muscle, spleen and lung indicated that labeled leukocytes had accumulated in those tissues and were mobilized to the circulation in response to exercise. This indicates that there is an ongoing exchange of leukocytes between the circulation and tissues and that exercise can stimulate their redistribution. Exchange was slower with muscle than with spleen and lung, but in all cases, influenced by exercise. Exercise bouts redistribute leukocytes between the circulation and the lung, spleen and muscle. The modulatory effects of exercise on the immune system may be regulated in part by the systemic redistribution of immune cells.

Acute effects of exercise on the inflammatory state in patients with idiopathic pulmonary arterial hypertension

“…A uniform response pattern seems to exist with a decrease in lymphocyte numbers in the spleen, accompanied by an increase in lymphocyte numbers in the lung, bone marrow and Peyer’s patches [2, 15, 26]. Accordingly, we observed a transient increase in the circulating lymphocyte numbers and also leukocyte numbers following exercise.…”

Effects of Exercise on microRNA Expression in Young Males Peripheral Blood Mononuclear Cells

“…reflect the overall microRNA response. Finally, this study was not designed to answer a key question that arises whenever one collects cells from the circulating blood—namely, are genomic or epigenetic changes observed in the circulating cells the direct result of exercise on those cells or, alternatively, do the differences derive from shifting genomically distinct populations of leukocytes as they migrate from marginal pools into the central circulation in response to exercise 1 . Nonetheless, either of these direct or indirect possibilities suggests an elegant, precise, and as of yet poorly understood mechanism that links exercise with immune cell function.…”

Lymphocytes and monocytes egress peripheral blood within minutes after cessation of steady state exercise: A detailed temporal analysis of leukocyte extravasation

“…Though this differentiation is not likely to occur in the 2 minutes of passive recovery, the monocytes might still home to areas where IL-6 is being produced. IL-6 also drives post-exercise NK-cell homing [46], and due to NK-cell tissue homing receptor densities they predominantly home to lung, spleen and muscle [47], where they can respond rapidly to opportunistic invading pathogens or reactivating viruses. It is likely that a combination of catecholamines, glucocorticoids and cytokines facilitate the rapid egress of discrete leukocyte subpopulations from the peripheral blood compartment after exercise allowing their homing to areas where reparative and sentinel action is required.…”